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Diffstat (limited to 'sql/opt_range.cc')
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diff --git a/sql/opt_range.cc b/sql/opt_range.cc new file mode 100644 index 00000000..9ec8781b --- /dev/null +++ b/sql/opt_range.cc @@ -0,0 +1,16562 @@ +/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. + Copyright (c) 2008, 2020, MariaDB + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; version 2 of the License. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */ + +/* + TODO: + Fix that MAYBE_KEY are stored in the tree so that we can detect use + of full hash keys for queries like: + + select s.id, kws.keyword_id from sites as s,kws where s.id=kws.site_id and kws.keyword_id in (204,205); + +*/ + +/* + This file contains: + + RangeAnalysisModule + A module that accepts a condition, index (or partitioning) description, + and builds lists of intervals (in index/partitioning space), such that + all possible records that match the condition are contained within the + intervals. + The entry point for the range analysis module is get_mm_tree() function. + + The lists are returned in form of complicated structure of interlinked + SEL_TREE/SEL_IMERGE/SEL_ARG objects. + See quick_range_seq_next, find_used_partitions for examples of how to walk + this structure. + All direct "users" of this module are located within this file, too. + + + PartitionPruningModule + A module that accepts a partitioned table, condition, and finds which + partitions we will need to use in query execution. Search down for + "PartitionPruningModule" for description. + The module has single entry point - prune_partitions() function. + + + Range/index_merge/groupby-minmax optimizer module + A module that accepts a table, condition, and returns + - a QUICK_*_SELECT object that can be used to retrieve rows that match + the specified condition, or a "no records will match the condition" + statement. + + The module entry points are + test_quick_select() + get_quick_select_for_ref() + + + Record retrieval code for range/index_merge/groupby-min-max. + Implementations of QUICK_*_SELECT classes. + + KeyTupleFormat + ~~~~~~~~~~~~~~ + The code in this file (and elsewhere) makes operations on key value tuples. + Those tuples are stored in the following format: + + The tuple is a sequence of key part values. The length of key part value + depends only on its type (and not depends on the what value is stored) + + KeyTuple: keypart1-data, keypart2-data, ... + + The value of each keypart is stored in the following format: + + keypart_data: [isnull_byte] keypart-value-bytes + + If a keypart may have a NULL value (key_part->field->real_maybe_null() can + be used to check this), then the first byte is a NULL indicator with the + following valid values: + 1 - keypart has NULL value. + 0 - keypart has non-NULL value. + + <questionable-statement> If isnull_byte==1 (NULL value), then the following + keypart->length bytes must be 0. + </questionable-statement> + + keypart-value-bytes holds the value. Its format depends on the field type. + The length of keypart-value-bytes may or may not depend on the value being + stored. The default is that length is static and equal to + KEY_PART_INFO::length. + + Key parts with (key_part_flag & HA_BLOB_PART) have length depending of the + value: + + keypart-value-bytes: value_length value_bytes + + The value_length part itself occupies HA_KEY_BLOB_LENGTH=2 bytes. + + See key_copy() and key_restore() for code to move data between index tuple + and table record + + CAUTION: the above description is only sergefp's understanding of the + subject and may omit some details. +*/ + +#ifdef USE_PRAGMA_IMPLEMENTATION +#pragma implementation // gcc: Class implementation +#endif + +#include "mariadb.h" +#include "sql_priv.h" +#include "key.h" // is_key_used, key_copy, key_cmp, key_restore +#include "sql_parse.h" // check_stack_overrun +#include "sql_partition.h" // get_part_id_func, PARTITION_ITERATOR, + // struct partition_info, NOT_A_PARTITION_ID +#include "records.h" // init_read_record, end_read_record +#include <m_ctype.h> +#include "sql_select.h" +#include "sql_statistics.h" +#include "uniques.h" +#include "my_json_writer.h" + +#ifndef EXTRA_DEBUG +#define test_rb_tree(A,B) {} +#define test_use_count(A) {} +#endif + +/* + Convert double value to #rows. Currently this does floor(), and we + might consider using round() instead. +*/ +#define double2rows(x) ((ha_rows)(x)) + +/* + this should be long enough so that any memcmp with a string that + starts from '\0' won't cross is_null_string boundaries, even + if the memcmp is optimized to compare 4- 8- or 16- bytes at once +*/ +static uchar is_null_string[20]= {1,0}; + +/** + Helper function to compare two SEL_ARG's. +*/ +static bool all_same(const SEL_ARG *sa1, const SEL_ARG *sa2) +{ + if (sa1 == NULL && sa2 == NULL) + return true; + if ((sa1 != NULL && sa2 == NULL) || (sa1 == NULL && sa2 != NULL)) + return false; + return sa1->all_same(sa2); +} + +class SEL_IMERGE; + +#define CLONE_KEY1_MAYBE 1 +#define CLONE_KEY2_MAYBE 2 +#define swap_clone_flag(A) ((A & 1) << 1) | ((A & 2) >> 1) + + +/* + While objects of the class SEL_ARG represent ranges for indexes or + index infixes (including ranges for index prefixes and index suffixes), + objects of the class SEL_TREE represent AND/OR formulas of such ranges. + Currently an AND/OR formula represented by a SEL_TREE object can have + at most three levels: + + <SEL_TREE formula> ::= + [ <SEL_RANGE_TREE formula> AND ] + [ <SEL_IMERGE formula> [ AND <SEL_IMERGE formula> ...] ] + + <SEL_RANGE_TREE formula> ::= + <SEL_ARG formula> [ AND <SEL_ARG_formula> ... ] + + <SEL_IMERGE formula> ::= + <SEL_RANGE_TREE formula> [ OR <SEL_RANGE_TREE formula> ] + + As we can see from the above definitions: + - SEL_RANGE_TREE formula is a conjunction of SEL_ARG formulas + - SEL_IMERGE formula is a disjunction of SEL_RANGE_TREE formulas + - SEL_TREE formula is a conjunction of a SEL_RANGE_TREE formula + and SEL_IMERGE formulas. + It's required above that a SEL_TREE formula has at least one conjunct. + + Usually we will consider normalized SEL_RANGE_TREE formulas where we use + TRUE as conjunct members for those indexes whose SEL_ARG trees are empty. + + We will call an SEL_TREE object simply 'tree'. + The part of a tree that represents SEL_RANGE_TREE formula is called + 'range part' of the tree while the remaining part is called 'imerge part'. + If a tree contains only a range part then we call such a tree 'range tree'. + Components of a range tree that represent SEL_ARG formulas are called ranges. + If a tree does not contain any range part we call such a tree 'imerge tree'. + Components of the imerge part of a tree that represent SEL_IMERGE formula + are called imerges. + + Usually we'll designate: + SEL_TREE formulas by T_1,...,T_k + SEL_ARG formulas by R_1,...,R_k + SEL_RANGE_TREE formulas by RT_1,...,RT_k + SEL_IMERGE formulas by M_1,...,M_k + Accordingly we'll use: + t_1,...,t_k - to designate trees representing T_1,...,T_k + r_1,...,r_k - to designate ranges representing R_1,...,R_k + rt_1,...,r_tk - to designate range trees representing RT_1,...,RT_k + m_1,...,m_k - to designate imerges representing M_1,...,M_k + + SEL_TREE objects are usually built from WHERE conditions or + ON expressions. + A SEL_TREE object always represents an inference of the condition it is + built from. Therefore, if a row satisfies a SEL_TREE formula it also + satisfies the condition it is built from. + + The following transformations of tree t representing SEL_TREE formula T + yield a new tree t1 thar represents an inference of T: T=>T1. + (1) remove any of SEL_ARG tree from the range part of t + (2) remove any imerge from the tree t + (3) remove any of SEL_ARG tree from any range tree contained + in any imerge of tree + + Since the basic blocks of any SEL_TREE objects are ranges, SEL_TREE + objects in many cases can be effectively used to filter out a big part + of table rows that do not satisfy WHERE/IN conditions utilizing + only single or multiple range index scans. + + A single range index scan is constructed for a range tree that contains + only one SEL_ARG object for an index or an index prefix. + An index intersection scan can be constructed for a range tree + that contains several SEL_ARG objects. Currently index intersection + scans are constructed only for single-point ranges. + An index merge scan is constructed for a imerge tree that contains only + one imerge. If range trees of this imerge contain only single-point merges + than a union of index intersections can be built. + + Usually the tree built by the range optimizer for a query table contains + more than one range in the range part, and additionally may contain some + imerges in the imerge part. The range optimizer evaluates all of them one + by one and chooses the range or the imerge that provides the cheapest + single or multiple range index scan of the table. According to rules + (1)-(3) this scan always filter out only those rows that do not satisfy + the query conditions. + + For any condition the SEL_TREE object for it is built in a bottom up + manner starting from the range trees for the predicates. The tree_and + function builds a tree for any conjunction of formulas from the trees + for its conjuncts. The tree_or function builds a tree for any disjunction + of formulas from the trees for its disjuncts. +*/ + +class SEL_TREE :public Sql_alloc +{ +public: + /* + Starting an effort to document this field: + (for some i, keys[i]->type == SEL_ARG::IMPOSSIBLE) => + (type == SEL_TREE::IMPOSSIBLE) + */ + enum Type { IMPOSSIBLE, ALWAYS, MAYBE, KEY, KEY_SMALLER } type; + + SEL_TREE(enum Type type_arg, MEM_ROOT *root, size_t num_keys) + : type(type_arg), keys(root, num_keys), n_ror_scans(0) + { + keys_map.clear_all(); + } + + SEL_TREE(MEM_ROOT *root, size_t num_keys) : + type(KEY), keys(root, num_keys), n_ror_scans(0) + { + keys_map.clear_all(); + } + + SEL_TREE(SEL_TREE *arg, bool without_merges, RANGE_OPT_PARAM *param); + /* + Note: there may exist SEL_TREE objects with sel_tree->type=KEY and + keys[i]=0 for all i. (SergeyP: it is not clear whether there is any + merit in range analyzer functions (e.g. get_mm_parts) returning a + pointer to such SEL_TREE instead of NULL) + */ + Mem_root_array<SEL_ARG *, true> keys; + key_map keys_map; /* bitmask of non-NULL elements in keys */ + + /* + Possible ways to read rows using index_merge. The list is non-empty only + if type==KEY. Currently can be non empty only if keys_map.is_clear_all(). + */ + List<SEL_IMERGE> merges; + + /* The members below are filled/used only after get_mm_tree is done */ + key_map ror_scans_map; /* bitmask of ROR scan-able elements in keys */ + uint n_ror_scans; /* number of set bits in ror_scans_map */ + + struct st_index_scan_info **index_scans; /* list of index scans */ + struct st_index_scan_info **index_scans_end; /* last index scan */ + + struct st_ror_scan_info **ror_scans; /* list of ROR key scans */ + struct st_ror_scan_info **ror_scans_end; /* last ROR scan */ + /* Note that #records for each key scan is stored in table->quick_rows */ + + bool without_ranges() { return keys_map.is_clear_all(); } + bool without_imerges() { return merges.is_empty(); } +}; + + +class PARAM : public RANGE_OPT_PARAM +{ +public: + ha_rows quick_rows[MAX_KEY]; + + /* + This will collect 'possible keys' based on the range optimization. + + Queries with a JOIN object actually use ref optimizer (see add_key_field) + to collect possible_keys. This is used by single table UPDATE/DELETE. + */ + key_map possible_keys; + longlong baseflag; + uint max_key_parts, range_count; + + bool quick; // Don't calulate possible keys + + uint fields_bitmap_size; + MY_BITMAP needed_fields; /* bitmask of fields needed by the query */ + MY_BITMAP tmp_covered_fields; + + key_map *needed_reg; /* ptr to SQL_SELECT::needed_reg */ + + uint *imerge_cost_buff; /* buffer for index_merge cost estimates */ + uint imerge_cost_buff_size; /* size of the buffer */ + + /* Number of ranges in the last checked tree->key */ + uint n_ranges; + uint8 first_null_comp; /* first null component if any, 0 - otherwise */ +}; + + +class TABLE_READ_PLAN; + class TRP_RANGE; + class TRP_ROR_INTERSECT; + class TRP_ROR_UNION; + class TRP_INDEX_INTERSECT; + class TRP_INDEX_MERGE; + class TRP_GROUP_MIN_MAX; + +struct st_index_scan_info; +struct st_ror_scan_info; + +static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts); +static ha_rows check_quick_select(PARAM *param, uint idx, bool index_only, + SEL_ARG *tree, bool update_tbl_stats, + uint *mrr_flags, uint *bufsize, + Cost_estimate *cost, bool *is_ror_scan); + +QUICK_RANGE_SELECT *get_quick_select(PARAM *param,uint index, + SEL_ARG *key_tree, uint mrr_flags, + uint mrr_buf_size, MEM_ROOT *alloc); +static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree, + bool index_read_must_be_used, + bool for_range_access, + double read_time); +static +TRP_INDEX_INTERSECT *get_best_index_intersect(PARAM *param, SEL_TREE *tree, + double read_time); +static +TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree, + double read_time, + bool *are_all_covering); +static +TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param, + SEL_TREE *tree, + double read_time); +static +TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge, + double read_time); +static +TABLE_READ_PLAN *merge_same_index_scans(PARAM *param, SEL_IMERGE *imerge, + TRP_INDEX_MERGE *imerge_trp, + double read_time); +static +TRP_GROUP_MIN_MAX *get_best_group_min_max(PARAM *param, SEL_TREE *tree, + double read_time); + +#ifndef DBUG_OFF +static void print_sel_tree(PARAM *param, SEL_TREE *tree, key_map *tree_map, + const char *msg); +static void print_ror_scans_arr(TABLE *table, const char *msg, + struct st_ror_scan_info **start, + struct st_ror_scan_info **end); +static void print_quick(QUICK_SELECT_I *quick, const key_map *needed_reg); +#endif + +static SEL_TREE *tree_and(RANGE_OPT_PARAM *param, + SEL_TREE *tree1, SEL_TREE *tree2); +static SEL_TREE *tree_or(RANGE_OPT_PARAM *param, + SEL_TREE *tree1,SEL_TREE *tree2); +static SEL_ARG *sel_add(SEL_ARG *key1,SEL_ARG *key2); +static SEL_ARG *key_or(RANGE_OPT_PARAM *param, + SEL_ARG *key1, SEL_ARG *key2); +static SEL_ARG *key_and(RANGE_OPT_PARAM *param, + SEL_ARG *key1, SEL_ARG *key2, + uint clone_flag); +static SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *key1, SEL_ARG *key2); +static SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *key1, SEL_ARG *key2, + uint clone_flag); +static bool get_range(SEL_ARG **e1,SEL_ARG **e2,SEL_ARG *root1); +bool get_quick_keys(PARAM *param,QUICK_RANGE_SELECT *quick,KEY_PART *key, + SEL_ARG *key_tree, uchar *min_key,uint min_key_flag, + uchar *max_key,uint max_key_flag); +static bool eq_tree(SEL_ARG* a,SEL_ARG *b); + +SEL_ARG null_element(SEL_ARG::IMPOSSIBLE); +static bool null_part_in_key(KEY_PART *key_part, const uchar *key, + uint length); +static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts); + +static +SEL_ARG *enforce_sel_arg_weight_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *sel_arg); +static +bool sel_arg_and_weight_heuristic(RANGE_OPT_PARAM *param, SEL_ARG *key1, + SEL_ARG *key2); + +#include "opt_range_mrr.cc" + +static bool sel_trees_have_common_keys(SEL_TREE *tree1, SEL_TREE *tree2, + key_map *common_keys); +static void eliminate_single_tree_imerges(RANGE_OPT_PARAM *param, + SEL_TREE *tree); + +static bool sel_trees_can_be_ored(RANGE_OPT_PARAM* param, + SEL_TREE *tree1, SEL_TREE *tree2, + key_map *common_keys); +static bool sel_trees_must_be_ored(RANGE_OPT_PARAM* param, + SEL_TREE *tree1, SEL_TREE *tree2, + key_map common_keys); +static int and_range_trees(RANGE_OPT_PARAM *param, + SEL_TREE *tree1, SEL_TREE *tree2, + SEL_TREE *result); +static bool remove_nonrange_trees(PARAM *param, SEL_TREE *tree); +static void restore_nonrange_trees(RANGE_OPT_PARAM *param, SEL_TREE *tree, + SEL_ARG **backup); +static void print_key_value(String *out, const KEY_PART_INFO *key_part, + const uchar* key, uint length); +static void print_keyparts_name(String *out, const KEY_PART_INFO *key_part, + uint n_keypart, key_part_map keypart_map); + +static void trace_ranges(Json_writer_array *range_trace, + PARAM *param, uint idx, + SEL_ARG *keypart, + const KEY_PART_INFO *key_parts); + +static +void print_range(String *out, const KEY_PART_INFO *key_part, + KEY_MULTI_RANGE *range, uint n_key_parts); + +static +void print_range_for_non_indexed_field(String *out, Field *field, + KEY_MULTI_RANGE *range); + +static void print_min_range_operator(String *out, const ha_rkey_function flag); +static void print_max_range_operator(String *out, const ha_rkey_function flag); + +static bool is_field_an_unique_index(RANGE_OPT_PARAM *param, Field *field); + +/* + SEL_IMERGE is a list of possible ways to do index merge, i.e. it is + a condition in the following form: + (t_1||t_2||...||t_N) && (next) + + where all t_i are SEL_TREEs, next is another SEL_IMERGE and no pair + (t_i,t_j) contains SEL_ARGS for the same index. + + SEL_TREE contained in SEL_IMERGE always has merges=NULL. + + This class relies on memory manager to do the cleanup. +*/ + +class SEL_IMERGE : public Sql_alloc +{ + enum { PREALLOCED_TREES= 10}; +public: + SEL_TREE *trees_prealloced[PREALLOCED_TREES]; + SEL_TREE **trees; /* trees used to do index_merge */ + SEL_TREE **trees_next; /* last of these trees */ + SEL_TREE **trees_end; /* end of allocated space */ + + SEL_ARG ***best_keys; /* best keys to read in SEL_TREEs */ + + SEL_IMERGE() : + trees(&trees_prealloced[0]), + trees_next(trees), + trees_end(trees + PREALLOCED_TREES) + {} + SEL_IMERGE (SEL_IMERGE *arg, uint cnt, RANGE_OPT_PARAM *param); + int or_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree); + bool have_common_keys(RANGE_OPT_PARAM *param, SEL_TREE *tree); + int and_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree, + SEL_IMERGE *new_imerge); + int or_sel_tree_with_checks(RANGE_OPT_PARAM *param, + uint n_init_trees, + SEL_TREE *new_tree, + bool is_first_check_pass, + bool *is_last_check_pass); + int or_sel_imerge_with_checks(RANGE_OPT_PARAM *param, + uint n_init_trees, + SEL_IMERGE* imerge, + bool is_first_check_pass, + bool *is_last_check_pass); +}; + + +/* + Add a range tree to the range trees of this imerge + + SYNOPSIS + or_sel_tree() + param Context info for the operation + tree SEL_TREE to add to this imerge + + DESCRIPTION + The function just adds the range tree 'tree' to the range trees + of this imerge. + + RETURN + 0 if the operation is success + -1 if the function runs out memory +*/ + +int SEL_IMERGE::or_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree) +{ + if (trees_next == trees_end) + { + const int realloc_ratio= 2; /* Double size for next round */ + size_t old_elements= (trees_end - trees); + size_t old_size= sizeof(SEL_TREE**) * old_elements; + size_t new_size= old_size * realloc_ratio; + SEL_TREE **new_trees; + if (!(new_trees= (SEL_TREE**)alloc_root(param->mem_root, new_size))) + return -1; + memcpy(new_trees, trees, old_size); + trees= new_trees; + trees_next= trees + old_elements; + trees_end= trees + old_elements * realloc_ratio; + } + *(trees_next++)= tree; + return 0; +} + + +/* + Check if any of the range trees of this imerge intersects with a given tree + + SYNOPSIS + have_common_keys() + param Context info for the function + tree SEL_TREE intersection with the imerge range trees is checked for + + DESCRIPTION + The function checks whether there is any range tree rt_i in this imerge + such that there are some indexes for which ranges are defined in both + rt_i and the range part of the SEL_TREE tree. + To check this the function calls the function sel_trees_have_common_keys. + + RETURN + TRUE if there are such range trees in this imerge + FALSE otherwise +*/ + +bool SEL_IMERGE::have_common_keys(RANGE_OPT_PARAM *param, SEL_TREE *tree) +{ + for (SEL_TREE** or_tree= trees, **bound= trees_next; + or_tree != bound; or_tree++) + { + key_map common_keys; + if (sel_trees_have_common_keys(*or_tree, tree, &common_keys)) + return TRUE; + } + return FALSE; +} + + +/* + Perform AND operation for this imerge and the range part of a tree + + SYNOPSIS + and_sel_tree() + param Context info for the operation + tree SEL_TREE for the second operand of the operation + new_imerge OUT imerge for the result of the operation + + DESCRIPTION + This function performs AND operation for this imerge m and the + range part of the SEL_TREE tree rt. In other words the function + pushes rt into this imerge. The resulting imerge is returned in + the parameter new_imerge. + If this imerge m represent the formula + RT_1 OR ... OR RT_k + then the resulting imerge of the function represents the formula + (RT_1 AND RT) OR ... OR (RT_k AND RT) + The function calls the function and_range_trees to construct the + range tree representing (RT_i AND RT). + + NOTE + The function may return an empty imerge without any range trees. + This happens when each call of and_range_trees returns an + impossible range tree (SEL_TREE::IMPOSSIBLE). + Example: (key1 < 2 AND key2 > 10) AND (key1 > 4 OR key2 < 6). + + RETURN + 0 if the operation is a success + -1 otherwise: there is not enough memory to perform the operation +*/ + +int SEL_IMERGE::and_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree, + SEL_IMERGE *new_imerge) +{ + for (SEL_TREE** or_tree= trees; or_tree != trees_next; or_tree++) + { + SEL_TREE *res_or_tree= 0; + SEL_TREE *and_tree= 0; + if (!(res_or_tree= new SEL_TREE(param->mem_root, param->keys)) || + !(and_tree= new SEL_TREE(tree, TRUE, param))) + return (-1); + if (!and_range_trees(param, *or_tree, and_tree, res_or_tree)) + { + if (new_imerge->or_sel_tree(param, res_or_tree)) + return (-1); + } + } + return 0; +} + + +/* + Perform OR operation on this imerge and the range part of a tree + + SYNOPSIS + or_sel_tree_with_checks() + param Context info for the operation + n_trees Number of trees in this imerge to check for oring + tree SEL_TREE whose range part is to be ored + is_first_check_pass <=> the first call of the function for this imerge + is_last_check_pass OUT <=> no more calls of the function for this imerge + + DESCRIPTION + The function performs OR operation on this imerge m and the range part + of the SEL_TREE tree rt. It always replaces this imerge with the result + of the operation. + + The operation can be performed in two different modes: with + is_first_check_pass==TRUE and is_first_check_pass==FALSE, transforming + this imerge differently. + + Given this imerge represents the formula + RT_1 OR ... OR RT_k: + + 1. In the first mode, when is_first_check_pass==TRUE : + 1.1. If rt must be ored(see the function sel_trees_must_be_ored) with + some rt_j (there may be only one such range tree in the imerge) + then the function produces an imerge representing the formula + RT_1 OR ... OR (RT_j OR RT) OR ... OR RT_k, + where the tree for (RT_j OR RT) is built by oring the pairs + of SEL_ARG trees for the corresponding indexes + 1.2. Otherwise the function produces the imerge representing the formula: + RT_1 OR ... OR RT_k OR RT. + + 2. In the second mode, when is_first_check_pass==FALSE : + 2.1. For each rt_j in the imerge that can be ored (see the function + sel_trees_can_be_ored) with rt the function replaces rt_j for a + range tree such that for each index for which ranges are defined + in both in rt_j and rt the tree contains the result of oring of + these ranges. + 2.2. In other cases the function does not produce any imerge. + + When is_first_check==TRUE the function returns FALSE in the parameter + is_last_check_pass if there is no rt_j such that rt_j can be ored with rt, + but, at the same time, it's not true that rt_j must be ored with rt. + When is_first_check==FALSE the function always returns FALSE in the + parameter is_last_check_pass. + + RETURN + 1 The result of oring of rt_j and rt that must be ored returns the + the range tree with type==SEL_TREE::ALWAYS + (in this case the imerge m should be discarded) + -1 The function runs out of memory + 0 in all other cases +*/ + +int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param, + uint n_trees, + SEL_TREE *tree, + bool is_first_check_pass, + bool *is_last_check_pass) +{ + bool was_ored= FALSE; + *is_last_check_pass= is_first_check_pass; + SEL_TREE** or_tree= trees; + for (uint i= 0; i < n_trees; i++, or_tree++) + { + SEL_TREE *result= 0; + key_map result_keys; + key_map ored_keys; + if (sel_trees_can_be_ored(param, *or_tree, tree, &ored_keys)) + { + bool must_be_ored= sel_trees_must_be_ored(param, *or_tree, tree, + ored_keys); + if (must_be_ored || !is_first_check_pass) + { + result_keys.clear_all(); + result= *or_tree; + for (uint key_no= 0; key_no < param->keys; key_no++) + { + if (!ored_keys.is_set(key_no)) + { + result->keys[key_no]= 0; + continue; + } + SEL_ARG *key1= (*or_tree)->keys[key_no]; + SEL_ARG *key2= tree->keys[key_no]; + key2->incr_refs(); + if ((result->keys[key_no]= key_or_with_limit(param, key_no, key1, + key2))) + { + + result_keys.set_bit(key_no); +#ifdef EXTRA_DEBUG + if (param->alloced_sel_args < SEL_ARG::MAX_SEL_ARGS) + { + key1= result->keys[key_no]; + (key1)->test_use_count(key1); + } +#endif + } + } + } + else if(is_first_check_pass) + *is_last_check_pass= FALSE; + } + + if (result) + { + result->keys_map= result_keys; + if (result_keys.is_clear_all()) + result->type= SEL_TREE::ALWAYS; + if ((result->type == SEL_TREE::MAYBE) || + (result->type == SEL_TREE::ALWAYS)) + return 1; + /* SEL_TREE::IMPOSSIBLE is impossible here */ + *or_tree= result; + was_ored= TRUE; + } + } + if (was_ored) + return 0; + + if (is_first_check_pass && !*is_last_check_pass && + !(tree= new SEL_TREE(tree, FALSE, param))) + return (-1); + return or_sel_tree(param, tree); +} + + +/* + Perform OR operation on this imerge and and another imerge + + SYNOPSIS + or_sel_imerge_with_checks() + param Context info for the operation + n_trees Number of trees in this imerge to check for oring + imerge The second operand of the operation + is_first_check_pass <=> the first call of the function for this imerge + is_last_check_pass OUT <=> no more calls of the function for this imerge + + DESCRIPTION + For each range tree rt from 'imerge' the function calls the method + SEL_IMERGE::or_sel_tree_with_checks that performs OR operation on this + SEL_IMERGE object m and the tree rt. The mode of the operation is + specified by the parameter is_first_check_pass. Each call of + SEL_IMERGE::or_sel_tree_with_checks transforms this SEL_IMERGE object m. + The function returns FALSE in the prameter is_last_check_pass if + at least one of the calls of SEL_IMERGE::or_sel_tree_with_checks + returns FALSE as the value of its last parameter. + + RETURN + 1 One of the calls of SEL_IMERGE::or_sel_tree_with_checks returns 1. + (in this case the imerge m should be discarded) + -1 The function runs out of memory + 0 in all other cases +*/ + +int SEL_IMERGE::or_sel_imerge_with_checks(RANGE_OPT_PARAM *param, + uint n_trees, + SEL_IMERGE* imerge, + bool is_first_check_pass, + bool *is_last_check_pass) +{ + *is_last_check_pass= TRUE; + SEL_TREE** tree= imerge->trees; + SEL_TREE** tree_end= imerge->trees_next; + for ( ; tree < tree_end; tree++) + { + uint rc; + bool is_last= TRUE; + rc= or_sel_tree_with_checks(param, n_trees, *tree, + is_first_check_pass, &is_last); + if (!is_last) + *is_last_check_pass= FALSE; + if (rc) + return rc; + } + return 0; +} + + +/* + Copy constructor for SEL_TREE objects + + SYNOPSIS + SEL_TREE + arg The source tree for the constructor + without_merges <=> only the range part of the tree arg is copied + param Context info for the operation + + DESCRIPTION + The constructor creates a full copy of the SEL_TREE arg if + the prameter without_merges==FALSE. Otherwise a tree is created + that contains the copy only of the range part of the tree arg. +*/ + +SEL_TREE::SEL_TREE(SEL_TREE *arg, bool without_merges, + RANGE_OPT_PARAM *param) + : Sql_alloc(), + keys(param->mem_root, param->keys), + n_ror_scans(0) +{ + keys_map= arg->keys_map; + type= arg->type; + MEM_ROOT *mem_root; + + for (uint idx= 0; idx < param->keys; idx++) + { + if ((keys[idx]= arg->keys[idx])) + keys[idx]->incr_refs_all(); + } + + if (without_merges) + return; + + mem_root= current_thd->mem_root; + List_iterator<SEL_IMERGE> it(arg->merges); + for (SEL_IMERGE *el= it++; el; el= it++) + { + SEL_IMERGE *merge= new (mem_root) SEL_IMERGE(el, 0, param); + if (!merge || merge->trees == merge->trees_next) + { + merges.empty(); + return; + } + merges.push_back(merge, mem_root); + } +} + + +/* + Copy constructor for SEL_IMERGE objects + + SYNOPSIS + SEL_IMERGE + arg The source imerge for the constructor + cnt How many trees from arg are to be copied + param Context info for the operation + + DESCRIPTION + The cnt==0 then the constructor creates a full copy of the + imerge arg. Otherwise only the first cnt trees of the imerge + are copied. +*/ + +SEL_IMERGE::SEL_IMERGE(SEL_IMERGE *arg, uint cnt, + RANGE_OPT_PARAM *param) : Sql_alloc() +{ + size_t elements= (arg->trees_end - arg->trees); + if (elements > PREALLOCED_TREES) + { + size_t size= elements * sizeof (SEL_TREE **); + if (!(trees= (SEL_TREE **)alloc_root(param->mem_root, size))) + goto mem_err; + } + else + trees= &trees_prealloced[0]; + + trees_next= trees + (cnt ? cnt : arg->trees_next-arg->trees); + trees_end= trees + elements; + + for (SEL_TREE **tree= trees, **arg_tree= arg->trees; tree < trees_next; + tree++, arg_tree++) + { + if (!(*tree= new SEL_TREE(*arg_tree, TRUE, param))) + goto mem_err; + } + + return; + +mem_err: + trees= &trees_prealloced[0]; + trees_next= trees; + trees_end= trees; +} + + +/* + Perform AND operation on two imerge lists + + SYNOPSIS + imerge_list_and_list() + param Context info for the operation + im1 The first imerge list for the operation + im2 The second imerge list for the operation + + DESCRIPTION + The function just appends the imerge list im2 to the imerge list im1 + + RETURN VALUE + none +*/ + +inline void imerge_list_and_list(List<SEL_IMERGE> *im1, List<SEL_IMERGE> *im2) +{ + im1->append(im2); +} + + +/* + Perform OR operation on two imerge lists + + SYNOPSIS + imerge_list_or_list() + param Context info for the operation + im1 The first imerge list for the operation + im2 The second imerge list for the operation + + DESCRIPTION + Assuming that the first imerge list represents the formula + F1= M1_1 AND ... AND M1_k1 + while the second imerge list represents the formula + F2= M2_1 AND ... AND M2_k2, + where M1_i= RT1_i_1 OR ... OR RT1_i_l1i (i in [1..k1]) + and M2_i = RT2_i_1 OR ... OR RT2_i_l2i (i in [1..k2]), + the function builds a list of imerges for some formula that can be + inferred from the formula (F1 OR F2). + + More exactly the function builds imerges for the formula (M1_1 OR M2_1). + Note that + (F1 OR F2) = (M1_1 AND ... AND M1_k1) OR (M2_1 AND ... AND M2_k2) = + AND (M1_i OR M2_j) (i in [1..k1], j in [1..k2]) => + M1_1 OR M2_1. + So (M1_1 OR M2_1) is indeed an inference formula for (F1 OR F2). + + To build imerges for the formula (M1_1 OR M2_1) the function invokes, + possibly twice, the method SEL_IMERGE::or_sel_imerge_with_checks + for the imerge m1_1. + At its first invocation the method SEL_IMERGE::or_sel_imerge_with_checks + performs OR operation on the imerge m1_1 and the range tree rt2_1_1 by + calling SEL_IMERGE::or_sel_tree_with_checks with is_first_pass_check==TRUE. + The resulting imerge of the operation is ored with the next range tree of + the imerge m2_1. This oring continues until the last range tree from + m2_1 has been ored. + At its second invocation the method SEL_IMERGE::or_sel_imerge_with_checks + performs the same sequence of OR operations, but now calling + SEL_IMERGE::or_sel_tree_with_checks with is_first_pass_check==FALSE. + + The imerges that the operation produces replace those in the list im1 + + RETURN + 0 if the operation is a success + -1 if the function has run out of memory +*/ + +int imerge_list_or_list(RANGE_OPT_PARAM *param, + List<SEL_IMERGE> *im1, + List<SEL_IMERGE> *im2) +{ + + uint rc; + bool is_last_check_pass= FALSE; + SEL_IMERGE *imerge= im1->head(); + uint elems= (uint)(imerge->trees_next-imerge->trees); + MEM_ROOT *mem_root= current_thd->mem_root; + + im1->empty(); + im1->push_back(imerge, mem_root); + + rc= imerge->or_sel_imerge_with_checks(param, elems, im2->head(), + TRUE, &is_last_check_pass); + if (rc) + { + if (rc == 1) + { + im1->empty(); + rc= 0; + } + return rc; + } + + if (!is_last_check_pass) + { + SEL_IMERGE* new_imerge= new (mem_root) SEL_IMERGE(imerge, elems, param); + if (new_imerge) + { + is_last_check_pass= TRUE; + rc= new_imerge->or_sel_imerge_with_checks(param, elems, im2->head(), + FALSE, &is_last_check_pass); + if (!rc) + im1->push_back(new_imerge, mem_root); + } + } + return rc; +} + + +/* + Perform OR operation for each imerge from a list and the range part of a tree + + SYNOPSIS + imerge_list_or_tree() + param Context info for the operation + merges The list of imerges to be ored with the range part of tree + tree SEL_TREE whose range part is to be ored with the imerges + + DESCRIPTION + For each imerge mi from the list 'merges' the function performes OR + operation with mi and the range part of 'tree' rt, producing one or + two imerges. + + Given the merge mi represent the formula RTi_1 OR ... OR RTi_k, + the function forms the merges by the following rules: + + 1. If rt cannot be ored with any of the trees rti the function just + produces an imerge that represents the formula + RTi_1 OR ... RTi_k OR RT. + 2. If there exist a tree rtj that must be ored with rt the function + produces an imerge the represents the formula + RTi_1 OR ... OR (RTi_j OR RT) OR ... OR RTi_k, + where the range tree for (RTi_j OR RT) is constructed by oring the + SEL_ARG trees that must be ored. + 3. For each rti_j that can be ored with rt the function produces + the new tree rti_j' and substitutes rti_j for this new range tree. + + In any case the function removes mi from the list and then adds all + produced imerges. + + To build imerges by rules 1-3 the function calls the method + SEL_IMERGE::or_sel_tree_with_checks, possibly twice. With the first + call it passes TRUE for the third parameter of the function. + At this first call imerges by rules 1-2 are built. If the call + returns FALSE as the return value of its fourth parameter then the + function are called for the second time. At this call the imerge + of rule 3 is produced. + + If a call of SEL_IMERGE::or_sel_tree_with_checks returns 1 then + then it means that the produced tree contains an always true + range tree and the whole imerge can be discarded. + + RETURN + 1 if no imerges are produced + 0 otherwise +*/ + +static +int imerge_list_or_tree(RANGE_OPT_PARAM *param, + List<SEL_IMERGE> *merges, + SEL_TREE *tree) +{ + SEL_IMERGE *imerge; + List<SEL_IMERGE> additional_merges; + List_iterator<SEL_IMERGE> it(*merges); + MEM_ROOT *mem_root= current_thd->mem_root; + + while ((imerge= it++)) + { + bool is_last_check_pass; + int rc= 0; + int rc1= 0; + SEL_TREE *or_tree= new (mem_root) SEL_TREE (tree, FALSE, param); + if (or_tree) + { + uint elems= (uint)(imerge->trees_next-imerge->trees); + rc= imerge->or_sel_tree_with_checks(param, elems, or_tree, + TRUE, &is_last_check_pass); + if (!is_last_check_pass) + { + SEL_IMERGE *new_imerge= new (mem_root) SEL_IMERGE(imerge, elems, + param); + if (new_imerge) + { + rc1= new_imerge->or_sel_tree_with_checks(param, elems, or_tree, + FALSE, &is_last_check_pass); + if (!rc1) + additional_merges.push_back(new_imerge, mem_root); + } + } + } + if (rc || rc1 || !or_tree) + it.remove(); + } + + merges->append(&additional_merges); + return merges->is_empty(); +} + + +/* + Perform pushdown operation of the range part of a tree into given imerges + + SYNOPSIS + imerge_list_and_tree() + param Context info for the operation + merges IN/OUT List of imerges to push the range part of 'tree' into + tree SEL_TREE whose range part is to be pushed into imerges + replace if the pushdow operation for a imerge is a success + then the original imerge is replaced for the result + of the pushdown + + DESCRIPTION + For each imerge from the list merges the function pushes the range part + rt of 'tree' into the imerge. + More exactly if the imerge mi from the list represents the formula + RTi_1 OR ... OR RTi_k + the function bulds a new imerge that represents the formula + (RTi_1 AND RT) OR ... OR (RTi_k AND RT) + and adds this imerge to the list merges. + To perform this pushdown operation the function calls the method + SEL_IMERGE::and_sel_tree. + For any imerge mi the new imerge is not created if for each pair of + trees rti_j and rt the intersection of the indexes with defined ranges + is empty. + If the result of the pushdown operation for the imerge mi returns an + imerge with no trees then then not only nothing is added to the list + merges but mi itself is removed from the list. + + TODO + Optimize the code in order to not create new SEL_IMERGE and new SER_TREE + objects when 'replace' is TRUE. (Currently this function is called always + with this parameter equal to TRUE.) + + RETURN + 1 if no imerges are left in the list merges + 0 otherwise +*/ + +static +int imerge_list_and_tree(RANGE_OPT_PARAM *param, + List<SEL_IMERGE> *merges, + SEL_TREE *tree, + bool replace) +{ + SEL_IMERGE *imerge; + SEL_IMERGE *new_imerge= NULL; + List<SEL_IMERGE> new_merges; + List_iterator<SEL_IMERGE> it(*merges); + MEM_ROOT *mem_root= current_thd->mem_root; + + while ((imerge= it++)) + { + if (!new_imerge) + new_imerge= new (mem_root) SEL_IMERGE(); + if (imerge->have_common_keys(param, tree) && + new_imerge && !imerge->and_sel_tree(param, tree, new_imerge)) + { + if (new_imerge->trees == new_imerge->trees_next) + it.remove(); + else + { + if (replace) + it.replace(new_imerge); + else + new_merges.push_back(new_imerge, mem_root); + new_imerge= NULL; + } + } + } + imerge_list_and_list(&new_merges, merges); + *merges= new_merges; + return merges->is_empty(); +} + + +/*************************************************************************** +** Basic functions for SQL_SELECT and QUICK_RANGE_SELECT +***************************************************************************/ + + /* make a select from mysql info + Error is set as following: + 0 = ok + 1 = Got some error (out of memory?) + */ + +SQL_SELECT *make_select(TABLE *head, table_map const_tables, + table_map read_tables, COND *conds, + SORT_INFO *filesort, + bool allow_null_cond, + int *error) +{ + SQL_SELECT *select; + DBUG_ENTER("make_select"); + + *error=0; + + if (!conds && !allow_null_cond) + DBUG_RETURN(0); + if (!(select= new (head->in_use->mem_root) SQL_SELECT)) + { + *error= 1; // out of memory + DBUG_RETURN(0); /* purecov: inspected */ + } + select->read_tables=read_tables; + select->const_tables=const_tables; + select->head=head; + select->cond= conds; + + if (filesort && my_b_inited(&filesort->io_cache)) + { + /* + Hijack the filesort io_cache for make_select + SQL_SELECT will be responsible for ensuring that it's properly freed. + */ + select->file= filesort->io_cache; + select->records=(ha_rows) (select->file.end_of_file/ + head->file->ref_length); + my_b_clear(&filesort->io_cache); + } + DBUG_RETURN(select); +} + + +SQL_SELECT::SQL_SELECT() :quick(0),cond(0),pre_idx_push_select_cond(NULL),free_cond(0) +{ + quick_keys.clear_all(); needed_reg.clear_all(); + my_b_clear(&file); +} + + +void SQL_SELECT::cleanup() +{ + delete quick; + quick= 0; + if (free_cond) + { + free_cond=0; + delete cond; + cond= 0; + } + close_cached_file(&file); +} + + +SQL_SELECT::~SQL_SELECT() +{ + cleanup(); +} + +#undef index // Fix for Unixware 7 + +QUICK_SELECT_I::QUICK_SELECT_I() + :max_used_key_length(0), + used_key_parts(0) +{} + +QUICK_RANGE_SELECT::QUICK_RANGE_SELECT(THD *thd, TABLE *table, uint key_nr, + bool no_alloc, MEM_ROOT *parent_alloc, + bool *create_error) + :thd(thd), no_alloc(no_alloc), parent_alloc(parent_alloc), + free_file(0),cur_range(NULL),last_range(0),dont_free(0) +{ + my_bitmap_map *bitmap; + DBUG_ENTER("QUICK_RANGE_SELECT::QUICK_RANGE_SELECT"); + + in_ror_merged_scan= 0; + index= key_nr; + head= table; + key_part_info= head->key_info[index].key_part; + + /* 'thd' is not accessible in QUICK_RANGE_SELECT::reset(). */ + mrr_buf_size= thd->variables.mrr_buff_size; + mrr_buf_desc= NULL; + + if (!no_alloc && !parent_alloc) + { + // Allocates everything through the internal memroot + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + thd->mem_root= &alloc; + } + else + bzero((char*) &alloc,sizeof(alloc)); + file= head->file; + record= head->record[0]; + + my_init_dynamic_array2(PSI_INSTRUMENT_ME, &ranges, sizeof(QUICK_RANGE*), + thd->alloc(sizeof(QUICK_RANGE*) * 16), 16, 16, + MYF(MY_THREAD_SPECIFIC)); + + /* Allocate a bitmap for used columns */ + if (!(bitmap= (my_bitmap_map*) thd->alloc(head->s->column_bitmap_size))) + { + column_bitmap.bitmap= 0; + *create_error= 1; + } + else + my_bitmap_init(&column_bitmap, bitmap, head->s->fields, FALSE); + DBUG_VOID_RETURN; +} + + +void QUICK_RANGE_SELECT::need_sorted_output() +{ + if (!(mrr_flags & HA_MRR_SORTED)) + { + /* + Native implementation can't produce sorted output. We'll have to + switch to default + */ + mrr_flags |= HA_MRR_USE_DEFAULT_IMPL; + } + mrr_flags |= HA_MRR_SORTED; +} + + +int QUICK_RANGE_SELECT::init() +{ + DBUG_ENTER("QUICK_RANGE_SELECT::init"); + + if (file->inited != handler::NONE) + file->ha_index_or_rnd_end(); + DBUG_RETURN(FALSE); +} + + +void QUICK_RANGE_SELECT::range_end() +{ + if (file->inited != handler::NONE) + file->ha_index_or_rnd_end(); +} + + +QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT() +{ + DBUG_ENTER("QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT"); + if (!dont_free) + { + /* file is NULL for CPK scan on covering ROR-intersection */ + if (file) + { + range_end(); + file->ha_end_keyread(); + if (free_file) + { + DBUG_PRINT("info", ("Freeing separate handler %p (free: %d)", file, + free_file)); + file->ha_external_unlock(current_thd); + file->ha_close(); + delete file; + } + } + delete_dynamic(&ranges); /* ranges are allocated in alloc */ + free_root(&alloc,MYF(0)); + } + my_free(mrr_buf_desc); + DBUG_VOID_RETURN; +} + +/* + QUICK_INDEX_SORT_SELECT works as follows: + - Do index scans, accumulate rowids in the Unique object + (Unique will also sort and de-duplicate rowids) + - Use rowids from unique to run a disk-ordered sweep +*/ + +QUICK_INDEX_SORT_SELECT::QUICK_INDEX_SORT_SELECT(THD *thd_param, TABLE *table) + :unique(NULL), pk_quick_select(NULL), thd(thd_param) +{ + DBUG_ENTER("QUICK_INDEX_SORT_SELECT::QUICK_INDEX_SORT_SELECT"); + index= MAX_KEY; + head= table; + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + DBUG_VOID_RETURN; +} + +int QUICK_INDEX_SORT_SELECT::init() +{ + DBUG_ENTER("QUICK_INDEX_SORT_SELECT::init"); + DBUG_RETURN(0); +} + +int QUICK_INDEX_SORT_SELECT::reset() +{ + DBUG_ENTER("QUICK_INDEX_SORT_SELECT::reset"); + const int retval= read_keys_and_merge(); + DBUG_RETURN(retval); +} + +bool +QUICK_INDEX_SORT_SELECT::push_quick_back(QUICK_RANGE_SELECT *quick_sel_range) +{ + DBUG_ENTER("QUICK_INDEX_SORT_SELECT::push_quick_back"); + if (head->file->is_clustering_key(quick_sel_range->index)) + { + /* + A quick_select over a clustered primary key is handled specifically + Here we assume: + - PK columns are included in any other merged index + - Scan on the PK is disk-ordered. + (not meeting #2 will only cause performance degradation) + + We could treat clustered PK as any other index, but that would + be inefficient. There is no point in doing scan on + CPK, remembering the rowid, then making rnd_pos() call with + that rowid. + */ + pk_quick_select= quick_sel_range; + DBUG_RETURN(0); + } + DBUG_RETURN(quick_selects.push_back(quick_sel_range, thd->mem_root)); +} + +QUICK_INDEX_SORT_SELECT::~QUICK_INDEX_SORT_SELECT() +{ + List_iterator_fast<QUICK_RANGE_SELECT> quick_it(quick_selects); + QUICK_RANGE_SELECT* quick; + DBUG_ENTER("QUICK_INDEX_SORT_SELECT::~QUICK_INDEX_SORT_SELECT"); + delete unique; + quick_it.rewind(); + while ((quick= quick_it++)) + quick->file= NULL; + quick_selects.delete_elements(); + delete pk_quick_select; + /* It's ok to call the next two even if they are already deinitialized */ + end_read_record(&read_record); + free_root(&alloc,MYF(0)); + DBUG_VOID_RETURN; +} + +QUICK_ROR_INTERSECT_SELECT::QUICK_ROR_INTERSECT_SELECT(THD *thd_param, + TABLE *table, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc) + : cpk_quick(NULL), thd(thd_param), need_to_fetch_row(retrieve_full_rows), + scans_inited(FALSE) +{ + index= MAX_KEY; + head= table; + record= head->record[0]; + if (!parent_alloc) + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + else + bzero(&alloc, sizeof(MEM_ROOT)); + last_rowid= (uchar*) alloc_root(parent_alloc? parent_alloc : &alloc, + head->file->ref_length); +} + + +/* + Do post-constructor initialization. + SYNOPSIS + QUICK_ROR_INTERSECT_SELECT::init() + + RETURN + 0 OK + other Error code +*/ + +int QUICK_ROR_INTERSECT_SELECT::init() +{ + DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::init"); + /* Check if last_rowid was successfully allocated in ctor */ + DBUG_RETURN(!last_rowid); +} + + +/* + Initialize this quick select to be a ROR-merged scan. + + SYNOPSIS + QUICK_RANGE_SELECT::init_ror_merged_scan() + reuse_handler If TRUE, use head->file, otherwise create a separate + handler object + + NOTES + This function creates and prepares for subsequent use a separate handler + object if it can't reuse head->file. The reason for this is that during + ROR-merge several key scans are performed simultaneously, and a single + handler is only capable of preserving context of a single key scan. + + In ROR-merge the quick select doing merge does full records retrieval, + merged quick selects read only keys. + + RETURN + 0 ROR child scan initialized, ok to use. + 1 error +*/ + +int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler, + MEM_ROOT *local_alloc) +{ + handler *save_file= file, *org_file; + THD *thd= head->in_use; + MY_BITMAP * const save_read_set= head->read_set; + MY_BITMAP * const save_write_set= head->write_set; + DBUG_ENTER("QUICK_RANGE_SELECT::init_ror_merged_scan"); + + in_ror_merged_scan= 1; + if (reuse_handler) + { + DBUG_PRINT("info", ("Reusing handler %p", file)); + if (init()) + { + DBUG_RETURN(1); + } + goto end; + } + + /* Create a separate handler object for this quick select */ + if (free_file) + { + /* already have own 'handler' object. */ + DBUG_RETURN(0); + } + + if (!(file= head->file->clone(head->s->normalized_path.str, local_alloc))) + { + /* + Manually set the error flag. Note: there seems to be quite a few + places where a failure could cause the server to "hang" the client by + sending no response to a query. ATM those are not real errors because + the storage engine calls in question happen to never fail with the + existing storage engines. + */ + my_error(ER_OUT_OF_RESOURCES, MYF(0)); /* purecov: inspected */ + /* Caller will free the memory */ + goto failure; /* purecov: inspected */ + } + + if (file->ha_external_lock(thd, F_RDLCK)) + goto failure; + + if (init()) + { + file->ha_external_unlock(thd); + file->ha_close(); + goto failure; + } + free_file= TRUE; + last_rowid= file->ref; + +end: + /* + We are only going to read key fields and call position() on 'file' + The following sets head->read_set (== column_bitmap) to only use this + key. The 'column_bitmap' is used in ::get_next() + */ + org_file= head->file; + head->file= file; + + head->column_bitmaps_set_no_signal(&column_bitmap, &column_bitmap); + head->prepare_for_keyread(index, &column_bitmap); + head->prepare_for_position(); + + head->file= org_file; + + /* Restore head->read_set (and write_set) to what they had before the call */ + head->column_bitmaps_set(save_read_set, save_write_set); + + if (reset()) + { + if (!reuse_handler) + { + file->ha_external_unlock(thd); + file->ha_close(); + goto failure; + } + DBUG_RETURN(1); + } + DBUG_RETURN(0); + +failure: + head->column_bitmaps_set(save_read_set, save_write_set); + delete file; + file= save_file; + free_file= false; + DBUG_RETURN(1); +} + + +/* + Initialize this quick select to be a part of a ROR-merged scan. + SYNOPSIS + QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan() + reuse_handler If TRUE, use head->file, otherwise create separate + handler object. + RETURN + 0 OK + other error code +*/ +int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler, + MEM_ROOT *local_alloc) +{ + List_iterator_fast<QUICK_SELECT_WITH_RECORD> quick_it(quick_selects); + QUICK_SELECT_WITH_RECORD *cur; + QUICK_RANGE_SELECT *quick; + DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan"); + + /* Initialize all merged "children" quick selects */ + DBUG_ASSERT(!need_to_fetch_row || reuse_handler); + if (!need_to_fetch_row && reuse_handler) + { + cur= quick_it++; + quick= cur->quick; + /* + There is no use of this->file. Use it for the first of merged range + selects. + */ + int error= quick->init_ror_merged_scan(TRUE, local_alloc); + if (unlikely(error)) + DBUG_RETURN(error); + quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS); + } + while ((cur= quick_it++)) + { + quick= cur->quick; +#ifndef DBUG_OFF + const MY_BITMAP * const save_read_set= quick->head->read_set; + const MY_BITMAP * const save_write_set= quick->head->write_set; +#endif + if (quick->init_ror_merged_scan(FALSE, local_alloc)) + DBUG_RETURN(1); + quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS); + + // Sets are shared by all members of "quick_selects" so must not change +#ifndef DBUG_OFF + DBUG_ASSERT(quick->head->read_set == save_read_set); + DBUG_ASSERT(quick->head->write_set == save_write_set); +#endif + /* All merged scans share the same record buffer in intersection. */ + quick->record= head->record[0]; + } + + if (need_to_fetch_row && + unlikely(head->file->ha_rnd_init_with_error(false))) + { + DBUG_PRINT("error", ("ROR index_merge rnd_init call failed")); + DBUG_RETURN(1); + } + DBUG_RETURN(0); +} + + +/* + Initialize quick select for row retrieval. + SYNOPSIS + reset() + RETURN + 0 OK + other Error code +*/ + +int QUICK_ROR_INTERSECT_SELECT::reset() +{ + DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::reset"); + if (!scans_inited && init_ror_merged_scan(TRUE, &alloc)) + DBUG_RETURN(1); + scans_inited= TRUE; + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + QUICK_SELECT_WITH_RECORD *qr; + while ((qr= it++)) + qr->quick->reset(); + DBUG_RETURN(0); +} + + +/* + Add a merged quick select to this ROR-intersection quick select. + + SYNOPSIS + QUICK_ROR_INTERSECT_SELECT::push_quick_back() + alloc Mem root to create auxiliary structures on + quick Quick select to be added. The quick select must return + rows in rowid order. + NOTES + This call can only be made before init() is called. + + RETURN + FALSE OK + TRUE Out of memory. +*/ + +bool +QUICK_ROR_INTERSECT_SELECT::push_quick_back(MEM_ROOT *local_alloc, + QUICK_RANGE_SELECT *quick) +{ + QUICK_SELECT_WITH_RECORD *qr; + if (!(qr= new QUICK_SELECT_WITH_RECORD) || + !(qr->key_tuple= (uchar*)alloc_root(local_alloc, + quick->max_used_key_length))) + return TRUE; + qr->quick= quick; + return quick_selects.push_back(qr); +} + + +QUICK_ROR_INTERSECT_SELECT::~QUICK_ROR_INTERSECT_SELECT() +{ + DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::~QUICK_ROR_INTERSECT_SELECT"); + quick_selects.delete_elements(); + delete cpk_quick; + free_root(&alloc,MYF(0)); + if (need_to_fetch_row && head->file->inited != handler::NONE) + head->file->ha_rnd_end(); + DBUG_VOID_RETURN; +} + + +QUICK_ROR_UNION_SELECT::QUICK_ROR_UNION_SELECT(THD *thd_param, + TABLE *table) + : thd(thd_param), scans_inited(FALSE) +{ + index= MAX_KEY; + head= table; + rowid_length= table->file->ref_length; + record= head->record[0]; + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + thd_param->mem_root= &alloc; +} + + +/* + Comparison function to be used QUICK_ROR_UNION_SELECT::queue priority + queue. + + SYNPOSIS + QUICK_ROR_UNION_SELECT_queue_cmp() + arg Pointer to QUICK_ROR_UNION_SELECT + val1 First merged select + val2 Second merged select +*/ + +C_MODE_START + +static int QUICK_ROR_UNION_SELECT_queue_cmp(void *arg, uchar *val1, uchar *val2) +{ + QUICK_ROR_UNION_SELECT *self= (QUICK_ROR_UNION_SELECT*)arg; + return self->head->file->cmp_ref(((QUICK_SELECT_I*)val1)->last_rowid, + ((QUICK_SELECT_I*)val2)->last_rowid); +} + +C_MODE_END + + +/* + Do post-constructor initialization. + SYNOPSIS + QUICK_ROR_UNION_SELECT::init() + + RETURN + 0 OK + other Error code +*/ + +int QUICK_ROR_UNION_SELECT::init() +{ + DBUG_ENTER("QUICK_ROR_UNION_SELECT::init"); + if (init_queue(&queue, quick_selects.elements, 0, + FALSE , QUICK_ROR_UNION_SELECT_queue_cmp, + (void*) this, 0, 0)) + { + bzero(&queue, sizeof(QUEUE)); + DBUG_RETURN(1); + } + + if (!(cur_rowid= (uchar*) alloc_root(&alloc, 2*head->file->ref_length))) + DBUG_RETURN(1); + prev_rowid= cur_rowid + head->file->ref_length; + DBUG_RETURN(0); +} + + +/* + Initialize quick select for row retrieval. + SYNOPSIS + reset() + + RETURN + 0 OK + other Error code +*/ + +int QUICK_ROR_UNION_SELECT::reset() +{ + QUICK_SELECT_I *quick; + int error; + DBUG_ENTER("QUICK_ROR_UNION_SELECT::reset"); + have_prev_rowid= FALSE; + if (!scans_inited) + { + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + while ((quick= it++)) + { + if (quick->init_ror_merged_scan(FALSE, &alloc)) + DBUG_RETURN(1); + } + scans_inited= TRUE; + } + queue_remove_all(&queue); + /* + Initialize scans for merged quick selects and put all merged quick + selects into the queue. + */ + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + while ((quick= it++)) + { + if (unlikely((error= quick->reset()))) + DBUG_RETURN(error); + if (unlikely((error= quick->get_next()))) + { + if (error == HA_ERR_END_OF_FILE) + continue; + DBUG_RETURN(error); + } + quick->save_last_pos(); + queue_insert(&queue, (uchar*)quick); + } + /* Prepare for ha_rnd_pos calls. */ + if (head->file->inited && unlikely((error= head->file->ha_rnd_end()))) + { + DBUG_PRINT("error", ("ROR index_merge rnd_end call failed")); + DBUG_RETURN(error); + } + if (unlikely((error= head->file->ha_rnd_init(false)))) + { + DBUG_PRINT("error", ("ROR index_merge rnd_init call failed")); + DBUG_RETURN(error); + } + + DBUG_RETURN(0); +} + + +bool +QUICK_ROR_UNION_SELECT::push_quick_back(QUICK_SELECT_I *quick_sel_range) +{ + return quick_selects.push_back(quick_sel_range); +} + +QUICK_ROR_UNION_SELECT::~QUICK_ROR_UNION_SELECT() +{ + DBUG_ENTER("QUICK_ROR_UNION_SELECT::~QUICK_ROR_UNION_SELECT"); + delete_queue(&queue); + quick_selects.delete_elements(); + if (head->file->inited != handler::NONE) + head->file->ha_rnd_end(); + free_root(&alloc,MYF(0)); + DBUG_VOID_RETURN; +} + + +QUICK_RANGE::QUICK_RANGE() + :min_key(0),max_key(0),min_length(0),max_length(0), + flag(NO_MIN_RANGE | NO_MAX_RANGE), + min_keypart_map(0), max_keypart_map(0) +{} + +SEL_ARG::SEL_ARG(SEL_ARG &arg) :Sql_alloc() +{ + type=arg.type; + min_flag=arg.min_flag; + max_flag=arg.max_flag; + maybe_flag=arg.maybe_flag; + maybe_null=arg.maybe_null; + part=arg.part; + field=arg.field; + min_value=arg.min_value; + max_value=arg.max_value; + next_key_part=arg.next_key_part; + max_part_no= arg.max_part_no; + use_count=1; elements=1; + weight=1; + next= 0; + if (next_key_part) + { + ++next_key_part->use_count; + weight += next_key_part->weight; + } +} + + +inline void SEL_ARG::make_root() +{ + left=right= &null_element; + color=BLACK; + next=prev=0; + use_count=0; elements=1; +} + +SEL_ARG::SEL_ARG(Field *f,const uchar *min_value_arg, + const uchar *max_value_arg) + :min_flag(0), max_flag(0), maybe_flag(0), maybe_null(f->real_maybe_null()), + elements(1), use_count(1), field(f), min_value((uchar*) min_value_arg), + max_value((uchar*) max_value_arg), next(0),prev(0), + next_key_part(0), color(BLACK), type(KEY_RANGE), weight(1) +{ + left=right= &null_element; + max_part_no= 1; +} + +SEL_ARG::SEL_ARG(Field *field_,uint8 part_, + uchar *min_value_, uchar *max_value_, + uint8 min_flag_,uint8 max_flag_,uint8 maybe_flag_) + :min_flag(min_flag_),max_flag(max_flag_),maybe_flag(maybe_flag_), + part(part_),maybe_null(field_->real_maybe_null()), elements(1),use_count(1), + field(field_), min_value(min_value_), max_value(max_value_), + next(0),prev(0),next_key_part(0),color(BLACK),type(KEY_RANGE), weight(1) +{ + max_part_no= part+1; + left=right= &null_element; +} + + +/* + A number of helper classes: + SEL_ARG_LE, SEL_ARG_LT, SEL_ARG_GT, SEL_ARG_GE, + to share the code between: + Field::stored_field_make_mm_leaf() + Field::stored_field_make_mm_leaf_exact() +*/ +class SEL_ARG_LE: public SEL_ARG +{ +public: + SEL_ARG_LE(const uchar *key, Field *field) + :SEL_ARG(field, key, key) + { + if (!field->real_maybe_null()) + min_flag= NO_MIN_RANGE; // From start + else + { + min_value= is_null_string; + min_flag= NEAR_MIN; // > NULL + } + } +}; + + +class SEL_ARG_LT: public SEL_ARG_LE +{ +public: + /* + Use this constructor if value->save_in_field() went precisely, + without any data rounding or truncation. + */ + SEL_ARG_LT(const uchar *key, Field *field) + :SEL_ARG_LE(key, field) + { max_flag= NEAR_MAX; } + /* + Use this constructor if value->save_in_field() returned success, + but we don't know if rounding or truncation happened + (as some Field::store() do not report minor data changes). + */ + SEL_ARG_LT(THD *thd, const uchar *key, Field *field, Item *value) + :SEL_ARG_LE(key, field) + { + if (stored_field_cmp_to_item(thd, field, value) == 0) + max_flag= NEAR_MAX; + } +}; + + +class SEL_ARG_GT: public SEL_ARG +{ +public: + /* + Use this constructor if value->save_in_field() went precisely, + without any data rounding or truncation. + */ + SEL_ARG_GT(const uchar *key, const KEY_PART *key_part, Field *field) + :SEL_ARG(field, key, key) + { + // Don't use open ranges for partial key_segments + if (!(key_part->flag & HA_PART_KEY_SEG)) + min_flag= NEAR_MIN; + max_flag= NO_MAX_RANGE; + } + /* + Use this constructor if value->save_in_field() returned success, + but we don't know if rounding or truncation happened + (as some Field::store() do not report minor data changes). + */ + SEL_ARG_GT(THD *thd, const uchar *key, + const KEY_PART *key_part, Field *field, Item *value) + :SEL_ARG(field, key, key) + { + // Don't use open ranges for partial key_segments + if ((!(key_part->flag & HA_PART_KEY_SEG)) && + (stored_field_cmp_to_item(thd, field, value) <= 0)) + min_flag= NEAR_MIN; + max_flag= NO_MAX_RANGE; + } +}; + + +class SEL_ARG_GE: public SEL_ARG +{ +public: + /* + Use this constructor if value->save_in_field() went precisely, + without any data rounding or truncation. + */ + SEL_ARG_GE(const uchar *key, Field *field) + :SEL_ARG(field, key, key) + { + max_flag= NO_MAX_RANGE; + } + /* + Use this constructor if value->save_in_field() returned success, + but we don't know if rounding or truncation happened + (as some Field::store() do not report minor data changes). + */ + SEL_ARG_GE(THD *thd, const uchar *key, + const KEY_PART *key_part, Field *field, Item *value) + :SEL_ARG(field, key, key) + { + // Don't use open ranges for partial key_segments + if ((!(key_part->flag & HA_PART_KEY_SEG)) && + (stored_field_cmp_to_item(thd, field, value) < 0)) + min_flag= NEAR_MIN; + max_flag= NO_MAX_RANGE; + } +}; + + +SEL_ARG *SEL_ARG::clone(RANGE_OPT_PARAM *param, SEL_ARG *new_parent, + SEL_ARG **next_arg) +{ + SEL_ARG *tmp; + + /* Bail out if we have already generated too many SEL_ARGs */ + if (++param->alloced_sel_args > MAX_SEL_ARGS) + return 0; + + if (type != KEY_RANGE) + { + if (!(tmp= new (param->mem_root) SEL_ARG(type))) + return 0; // out of memory + tmp->prev= *next_arg; // Link into next/prev chain + (*next_arg)->next=tmp; + (*next_arg)= tmp; + tmp->part= this->part; + } + else + { + if (!(tmp= new (param->mem_root) SEL_ARG(field,part, min_value,max_value, + min_flag, max_flag, maybe_flag))) + return 0; // OOM + tmp->parent=new_parent; + tmp->next_key_part=next_key_part; + if (left != &null_element) + if (!(tmp->left=left->clone(param, tmp, next_arg))) + return 0; // OOM + + tmp->prev= *next_arg; // Link into next/prev chain + (*next_arg)->next=tmp; + (*next_arg)= tmp; + + if (right != &null_element) + if (!(tmp->right= right->clone(param, tmp, next_arg))) + return 0; // OOM + } + increment_use_count(1); + tmp->color= color; + tmp->elements= this->elements; + tmp->max_part_no= max_part_no; + tmp->weight= weight; + return tmp; +} + +/** + This gives the first SEL_ARG in the interval list, and the minimal element + in the red-black tree + + @return + SEL_ARG first SEL_ARG in the interval list +*/ +SEL_ARG *SEL_ARG::first() +{ + SEL_ARG *next_arg=this; + if (!next_arg->left) + return 0; // MAYBE_KEY + while (next_arg->left != &null_element) + next_arg=next_arg->left; + return next_arg; +} + +const SEL_ARG *SEL_ARG::first() const +{ + return const_cast<SEL_ARG*>(this)->first(); +} + +SEL_ARG *SEL_ARG::last() +{ + SEL_ARG *next_arg=this; + if (!next_arg->right) + return 0; // MAYBE_KEY + while (next_arg->right != &null_element) + next_arg=next_arg->right; + return next_arg; +} + + +/* + Check if a compare is ok, when one takes ranges in account + Returns -2 or 2 if the ranges where 'joined' like < 2 and >= 2 +*/ + +int SEL_ARG::sel_cmp(Field *field, uchar *a, uchar *b, uint8 a_flag, + uint8 b_flag) +{ + int cmp; + /* First check if there was a compare to a min or max element */ + if (a_flag & (NO_MIN_RANGE | NO_MAX_RANGE)) + { + if ((a_flag & (NO_MIN_RANGE | NO_MAX_RANGE)) == + (b_flag & (NO_MIN_RANGE | NO_MAX_RANGE))) + return 0; + return (a_flag & NO_MIN_RANGE) ? -1 : 1; + } + if (b_flag & (NO_MIN_RANGE | NO_MAX_RANGE)) + return (b_flag & NO_MIN_RANGE) ? 1 : -1; + + if (field->real_maybe_null()) // If null is part of key + { + if (*a != *b) + { + return *a ? -1 : 1; + } + if (*a) + goto end; // NULL where equal + a++; b++; // Skip NULL marker + } + cmp=field->key_cmp(a , b); + if (cmp) return cmp < 0 ? -1 : 1; // The values differed + + // Check if the compared equal arguments was defined with open/closed range + end: + if (a_flag & (NEAR_MIN | NEAR_MAX)) + { + if ((a_flag & (NEAR_MIN | NEAR_MAX)) == (b_flag & (NEAR_MIN | NEAR_MAX))) + return 0; + if (!(b_flag & (NEAR_MIN | NEAR_MAX))) + return (a_flag & NEAR_MIN) ? 2 : -2; + return (a_flag & NEAR_MIN) ? 1 : -1; + } + if (b_flag & (NEAR_MIN | NEAR_MAX)) + return (b_flag & NEAR_MIN) ? -2 : 2; + return 0; // The elements where equal +} + + +SEL_ARG *SEL_ARG::clone_tree(RANGE_OPT_PARAM *param) +{ + SEL_ARG tmp_link,*next_arg,*root; + next_arg= &tmp_link; + if (!(root= clone(param, (SEL_ARG *) 0, &next_arg))) + return 0; + next_arg->next=0; // Fix last link + tmp_link.next->prev=0; // Fix first link + if (root) // If not OOM + root->use_count= 0; + return root; +} + + +/* + Table rows retrieval plan. Range optimizer creates QUICK_SELECT_I-derived + objects from table read plans. +*/ +class TABLE_READ_PLAN +{ +public: + /* + Plan read cost, with or without cost of full row retrieval, depending + on plan creation parameters. + */ + double read_cost; + ha_rows records; /* estimate of #rows to be examined */ + + /* + If TRUE, the scan returns rows in rowid order. This is used only for + scans that can be both ROR and non-ROR. + */ + bool is_ror; + + /* + Create quick select for this plan. + SYNOPSIS + make_quick() + param Parameter from test_quick_select + retrieve_full_rows If TRUE, created quick select will do full record + retrieval. + parent_alloc Memory pool to use, if any. + + NOTES + retrieve_full_rows is ignored by some implementations. + + RETURN + created quick select + NULL on any error. + */ + virtual QUICK_SELECT_I *make_quick(PARAM *param, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc=NULL) = 0; + + /* Table read plans are allocated on MEM_ROOT and are never deleted */ + static void *operator new(size_t size, MEM_ROOT *mem_root) + { return (void*) alloc_root(mem_root, (uint) size); } + static void operator delete(void *ptr,size_t size) { TRASH_FREE(ptr, size); } + static void operator delete(void *ptr, MEM_ROOT *mem_root) { /* Never called */ } + virtual ~TABLE_READ_PLAN() {} /* Remove gcc warning */ + /** + Add basic info for this TABLE_READ_PLAN to the optimizer trace. + + @param param Parameters for range analysis of this table + @param trace_object The optimizer trace object the info is appended to + */ + virtual void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const= 0; + +}; + +class TRP_ROR_INTERSECT; +class TRP_ROR_UNION; +class TRP_INDEX_MERGE; + + +/* + Plan for a QUICK_RANGE_SELECT scan. + TRP_RANGE::make_quick ignores retrieve_full_rows parameter because + QUICK_RANGE_SELECT doesn't distinguish between 'index only' scans and full + record retrieval scans. +*/ + +class TRP_RANGE : public TABLE_READ_PLAN +{ +public: + SEL_ARG *key; /* set of intervals to be used in "range" method retrieval */ + uint key_idx; /* key number in PARAM::key */ + uint mrr_flags; + uint mrr_buf_size; + + TRP_RANGE(SEL_ARG *key_arg, uint idx_arg, uint mrr_flags_arg) + : key(key_arg), key_idx(idx_arg), mrr_flags(mrr_flags_arg) + {} + virtual ~TRP_RANGE() {} /* Remove gcc warning */ + + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc) + { + DBUG_ENTER("TRP_RANGE::make_quick"); + QUICK_RANGE_SELECT *quick; + if ((quick= get_quick_select(param, key_idx, key, mrr_flags, + mrr_buf_size, parent_alloc))) + { + quick->records= records; + quick->read_time= read_cost; + } + DBUG_RETURN(quick); + } + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; +}; + +void TRP_RANGE::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + DBUG_ASSERT(trace_object->trace_started()); + DBUG_ASSERT(param->using_real_indexes); + const uint keynr_in_table= param->real_keynr[key_idx]; + + const KEY &cur_key= param->table->key_info[keynr_in_table]; + const KEY_PART_INFO *key_part= cur_key.key_part; + + trace_object->add("type", "range_scan") + .add("index", cur_key.name) + .add("rows", records); + + Json_writer_array trace_range(param->thd, "ranges"); + + // TRP_RANGE should not be created if there are no range intervals + DBUG_ASSERT(key); + + trace_ranges(&trace_range, param, key_idx, key, key_part); +} + + +/* Plan for QUICK_ROR_INTERSECT_SELECT scan. */ + +class TRP_ROR_INTERSECT : public TABLE_READ_PLAN +{ +public: + TRP_ROR_INTERSECT() {} /* Remove gcc warning */ + virtual ~TRP_ROR_INTERSECT() {} /* Remove gcc warning */ + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc); + + /* Array of pointers to ROR range scans used in this intersection */ + struct st_ror_scan_info **first_scan; + struct st_ror_scan_info **last_scan; /* End of the above array */ + struct st_ror_scan_info *cpk_scan; /* Clustered PK scan, if there is one */ + bool is_covering; /* TRUE if no row retrieval phase is necessary */ + double index_scan_costs; /* SUM(cost(index_scan)) */ + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; +}; + + + +/* + Plan for QUICK_ROR_UNION_SELECT scan. + QUICK_ROR_UNION_SELECT always retrieves full rows, so retrieve_full_rows + is ignored by make_quick. +*/ + +class TRP_ROR_UNION : public TABLE_READ_PLAN +{ +public: + TRP_ROR_UNION() {} /* Remove gcc warning */ + virtual ~TRP_ROR_UNION() {} /* Remove gcc warning */ + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc); + TABLE_READ_PLAN **first_ror; /* array of ptrs to plans for merged scans */ + TABLE_READ_PLAN **last_ror; /* end of the above array */ + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; +}; + +void TRP_ROR_UNION::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + THD *thd= param->thd; + DBUG_ASSERT(trace_object->trace_started()); + trace_object->add("type", "index_roworder_union"); + Json_writer_array smth_trace(thd, "union_of"); + for (TABLE_READ_PLAN **current= first_ror; current != last_ror; current++) + { + Json_writer_object trp_info(thd); + (*current)->trace_basic_info(param, &trp_info); + } +} + +/* + Plan for QUICK_INDEX_INTERSECT_SELECT scan. + QUICK_INDEX_INTERSECT_SELECT always retrieves full rows, so retrieve_full_rows + is ignored by make_quick. +*/ + +class TRP_INDEX_INTERSECT : public TABLE_READ_PLAN +{ +public: + TRP_INDEX_INTERSECT() {} /* Remove gcc warning */ + virtual ~TRP_INDEX_INTERSECT() {} /* Remove gcc warning */ + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc); + TRP_RANGE **range_scans; /* array of ptrs to plans of intersected scans */ + TRP_RANGE **range_scans_end; /* end of the array */ + /* keys whose scans are to be filtered by cpk conditions */ + key_map filtered_scans; + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; + +}; + +void TRP_INDEX_INTERSECT::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + THD *thd= param->thd; + DBUG_ASSERT(trace_object->trace_started()); + trace_object->add("type", "index_sort_intersect"); + Json_writer_array smth_trace(thd, "index_sort_intersect_of"); + for (TRP_RANGE **current= range_scans; current != range_scans_end; + current++) + { + Json_writer_object trp_info(thd); + (*current)->trace_basic_info(param, &trp_info); + } +} + +/* + Plan for QUICK_INDEX_MERGE_SELECT scan. + QUICK_ROR_INTERSECT_SELECT always retrieves full rows, so retrieve_full_rows + is ignored by make_quick. +*/ + +class TRP_INDEX_MERGE : public TABLE_READ_PLAN +{ +public: + TRP_INDEX_MERGE() {} /* Remove gcc warning */ + virtual ~TRP_INDEX_MERGE() {} /* Remove gcc warning */ + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc); + TRP_RANGE **range_scans; /* array of ptrs to plans of merged scans */ + TRP_RANGE **range_scans_end; /* end of the array */ + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; +}; + +void TRP_INDEX_MERGE::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + THD *thd= param->thd; + DBUG_ASSERT(trace_object->trace_started()); + trace_object->add("type", "index_merge"); + Json_writer_array smth_trace(thd, "index_merge_of"); + for (TRP_RANGE **current= range_scans; current != range_scans_end; current++) + { + Json_writer_object trp_info(thd); + (*current)->trace_basic_info(param, &trp_info); + } +} + +/* + Plan for a QUICK_GROUP_MIN_MAX_SELECT scan. +*/ + +class TRP_GROUP_MIN_MAX : public TABLE_READ_PLAN +{ +private: + bool have_min, have_max, have_agg_distinct; + KEY_PART_INFO *min_max_arg_part; + uint group_prefix_len; + uint used_key_parts; + uint group_key_parts; + KEY *index_info; + uint index; + uint key_infix_len; + uchar key_infix[MAX_KEY_LENGTH]; + SEL_TREE *range_tree; /* Represents all range predicates in the query. */ + SEL_ARG *index_tree; /* The SEL_ARG sub-tree corresponding to index_info. */ + uint param_idx; /* Index of used key in param->key. */ + bool is_index_scan; /* Use index_next() instead of random read */ +public: + /* Number of records selected by the ranges in index_tree. */ + ha_rows quick_prefix_records; +public: + TRP_GROUP_MIN_MAX(bool have_min_arg, bool have_max_arg, + bool have_agg_distinct_arg, + KEY_PART_INFO *min_max_arg_part_arg, + uint group_prefix_len_arg, uint used_key_parts_arg, + uint group_key_parts_arg, KEY *index_info_arg, + uint index_arg, uint key_infix_len_arg, + uchar *key_infix_arg, + SEL_TREE *tree_arg, SEL_ARG *index_tree_arg, + uint param_idx_arg, ha_rows quick_prefix_records_arg) + : have_min(have_min_arg), have_max(have_max_arg), + have_agg_distinct(have_agg_distinct_arg), + min_max_arg_part(min_max_arg_part_arg), + group_prefix_len(group_prefix_len_arg), used_key_parts(used_key_parts_arg), + group_key_parts(group_key_parts_arg), index_info(index_info_arg), + index(index_arg), key_infix_len(key_infix_len_arg), range_tree(tree_arg), + index_tree(index_tree_arg), param_idx(param_idx_arg), is_index_scan(FALSE), + quick_prefix_records(quick_prefix_records_arg) + { + if (key_infix_len) + memcpy(this->key_infix, key_infix_arg, key_infix_len); + } + virtual ~TRP_GROUP_MIN_MAX() {} /* Remove gcc warning */ + + QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc); + void use_index_scan() { is_index_scan= TRUE; } + void trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const; +}; + + +void TRP_GROUP_MIN_MAX::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + THD *thd= param->thd; + DBUG_ASSERT(trace_object->trace_started()); + + trace_object->add("type", "index_group").add("index", index_info->name); + + if (min_max_arg_part) + trace_object->add("min_max_arg", min_max_arg_part->field->field_name); + else + trace_object->add_null("min_max_arg"); + + trace_object->add("min_aggregate", have_min) + .add("max_aggregate", have_max) + .add("distinct_aggregate", have_agg_distinct) + .add("rows", records) + .add("cost", read_cost); + + const KEY_PART_INFO *key_part= index_info->key_part; + { + Json_writer_array trace_keyparts(thd, "key_parts_used_for_access"); + for (uint partno= 0; partno < used_key_parts; partno++) + { + const KEY_PART_INFO *cur_key_part= key_part + partno; + trace_keyparts.add(cur_key_part->field->field_name); + } + } + + Json_writer_array trace_range(thd, "ranges"); + + // can have group quick without ranges + if (index_tree) + { + trace_ranges(&trace_range, param, param_idx, + index_tree, key_part); + } +} + + +typedef struct st_index_scan_info +{ + uint idx; /* # of used key in param->keys */ + uint keynr; /* # of used key in table */ + uint range_count; + ha_rows records; /* estimate of # records this scan will return */ + + /* Set of intervals over key fields that will be used for row retrieval. */ + SEL_ARG *sel_arg; + + KEY *key_info; + uint used_key_parts; + + /* Estimate of # records filtered out by intersection with cpk */ + ha_rows filtered_out; + /* Bitmap of fields used in index intersection */ + MY_BITMAP used_fields; + + /* Fields used in the query and covered by ROR scan. */ + MY_BITMAP covered_fields; + uint used_fields_covered; /* # of set bits in covered_fields */ + int key_rec_length; /* length of key record (including rowid) */ + + /* + Cost of reading all index records with values in sel_arg intervals set + (assuming there is no need to access full table records) + */ + double index_read_cost; + uint first_uncovered_field; /* first unused bit in covered_fields */ + uint key_components; /* # of parts in the key */ +} INDEX_SCAN_INFO; + +/* + Fill param->needed_fields with bitmap of fields used in the query. + SYNOPSIS + fill_used_fields_bitmap() + param Parameter from test_quick_select function. + + NOTES + Clustered PK members are not put into the bitmap as they are implicitly + present in all keys (and it is impossible to avoid reading them). + RETURN + 0 Ok + 1 Out of memory. +*/ + +static int fill_used_fields_bitmap(PARAM *param) +{ + TABLE *table= param->table; + my_bitmap_map *tmp; + uint pk; + param->tmp_covered_fields.bitmap= 0; + param->fields_bitmap_size= table->s->column_bitmap_size; + if (!(tmp= (my_bitmap_map*) alloc_root(param->mem_root, + param->fields_bitmap_size)) || + my_bitmap_init(¶m->needed_fields, tmp, table->s->fields, FALSE)) + return 1; + + bitmap_copy(¶m->needed_fields, table->read_set); + bitmap_union(¶m->needed_fields, table->write_set); + + pk= param->table->s->primary_key; + if (param->table->file->pk_is_clustering_key(pk)) + { + /* The table uses clustered PK and it is not internally generated */ + KEY_PART_INFO *key_part= param->table->key_info[pk].key_part; + KEY_PART_INFO *key_part_end= key_part + + param->table->key_info[pk].user_defined_key_parts; + for (;key_part != key_part_end; ++key_part) + bitmap_clear_bit(¶m->needed_fields, key_part->fieldnr-1); + } + return 0; +} + + +/* + Test if a key can be used in different ranges + + SYNOPSIS + SQL_SELECT::test_quick_select() + thd Current thread + keys_to_use Keys to use for range retrieval + prev_tables Tables assumed to be already read when the scan is + performed (but not read at the moment of this call) + limit Query limit + force_quick_range Prefer to use range (instead of full table scan) even + if it is more expensive. + remove_false_parts_of_where Remove parts of OR-clauses for which range + analysis produced SEL_TREE(IMPOSSIBLE) + only_single_index_range_scan Evaluate only single index range scans + + NOTES + Updates the following in the select parameter: + needed_reg - Bits for keys with may be used if all prev regs are read + quick - Parameter to use when reading records. + + In the table struct the following information is updated: + quick_keys - Which keys can be used + quick_rows - How many rows the key matches + opt_range_condition_rows - E(# rows that will satisfy the table condition) + + IMPLEMENTATION + opt_range_condition_rows value is obtained as follows: + + It is a minimum of E(#output rows) for all considered table access + methods (range and index_merge accesses over various indexes). + + The obtained value is not a true E(#rows that satisfy table condition) + but rather a pessimistic estimate. To obtain a true E(#...) one would + need to combine estimates of various access methods, taking into account + correlations between sets of rows they will return. + + For example, if values of tbl.key1 and tbl.key2 are independent (a right + assumption if we have no information about their correlation) then the + correct estimate will be: + + E(#rows("tbl.key1 < c1 AND tbl.key2 < c2")) = + = E(#rows(tbl.key1 < c1)) / total_rows(tbl) * E(#rows(tbl.key2 < c2) + + which is smaller than + + MIN(E(#rows(tbl.key1 < c1), E(#rows(tbl.key2 < c2))) + + which is currently produced. + + TODO + * Change the value returned in opt_range_condition_rows from a pessimistic + estimate to true E(#rows that satisfy table condition). + (we can re-use some of E(#rows) calcuation code from + index_merge/intersection for this) + + * Check if this function really needs to modify keys_to_use, and change the + code to pass it by reference if it doesn't. + + * In addition to force_quick_range other means can be (an usually are) used + to make this function prefer range over full table scan. Figure out if + force_quick_range is really needed. + + RETURN + -1 if error or impossible select (i.e. certainly no rows will be selected) + 0 if can't use quick_select + 1 if found usable ranges and quick select has been successfully created. +*/ + +int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use, + table_map prev_tables, + ha_rows limit, bool force_quick_range, + bool ordered_output, + bool remove_false_parts_of_where, + bool only_single_index_range_scan) +{ + uint idx; + double scan_time; + Item *notnull_cond= NULL; + TABLE_READ_PLAN *best_trp= NULL; + SEL_ARG **backup_keys= 0; + DBUG_ENTER("SQL_SELECT::test_quick_select"); + DBUG_PRINT("enter",("keys_to_use: %lu prev_tables: %lu const_tables: %lu", + (ulong) keys_to_use.to_ulonglong(), (ulong) prev_tables, + (ulong) const_tables)); + DBUG_PRINT("info", ("records: %lu", (ulong) head->stat_records())); + delete quick; + quick=0; + needed_reg.clear_all(); + quick_keys.clear_all(); + head->with_impossible_ranges.clear_all(); + DBUG_ASSERT(!head->is_filled_at_execution()); + if (keys_to_use.is_clear_all() || head->is_filled_at_execution()) + DBUG_RETURN(0); + records= head->stat_records(); + notnull_cond= head->notnull_cond; + if (!records) + records++; /* purecov: inspected */ + + if (head->force_index || force_quick_range) + scan_time= read_time= DBL_MAX; + else + { + scan_time= rows2double(records) / TIME_FOR_COMPARE; + /* + The 2 is there to prefer range scans to full table scans. + This is mainly to make the test suite happy as many tests has + very few rows. In real life tables has more than a few rows and the + +2 has no practical effect. + */ + read_time= (double) head->file->scan_time() + scan_time + 2; + if (limit < records && read_time < (double) records + scan_time + 1 ) + { + read_time= (double) records + scan_time + 1; // Force to use index + notnull_cond= NULL; + } + } + + possible_keys.clear_all(); + + DBUG_PRINT("info",("Time to scan table: %g", read_time)); + + Json_writer_object table_records(thd); + table_records.add_table_name(head); + + Json_writer_object trace_range(thd, "range_analysis"); + { + Json_writer_object table_rec(thd, "table_scan"); + table_rec.add("rows", records).add("cost", read_time); + } + + keys_to_use.intersect(head->keys_in_use_for_query); + if (!keys_to_use.is_clear_all()) + { + uchar buff[STACK_BUFF_ALLOC]; + MEM_ROOT alloc; + SEL_TREE *tree= NULL; + SEL_TREE *notnull_cond_tree= NULL; + KEY_PART *key_parts; + KEY *key_info; + PARAM param; + bool force_group_by = false; + + if (check_stack_overrun(thd, 2*STACK_MIN_SIZE + sizeof(PARAM), buff)) + DBUG_RETURN(0); // Fatal error flag is set + + /* set up parameter that is passed to all functions */ + param.thd= thd; + param.baseflag= head->file->ha_table_flags(); + param.prev_tables=prev_tables | const_tables; + param.read_tables=read_tables; + param.current_table= head->map; + param.table=head; + param.keys=0; + param.mem_root= &alloc; + param.old_root= thd->mem_root; + param.needed_reg= &needed_reg; + param.imerge_cost_buff_size= 0; + param.using_real_indexes= TRUE; + param.remove_jump_scans= TRUE; + param.max_key_parts= 0; + param.remove_false_where_parts= remove_false_parts_of_where; + param.force_default_mrr= ordered_output; + param.possible_keys.clear_all(); + + thd->no_errors=1; // Don't warn about NULL + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + if (!(param.key_parts= + (KEY_PART*) alloc_root(&alloc, + sizeof(KEY_PART) * + head->s->actual_n_key_parts(thd))) || + fill_used_fields_bitmap(¶m)) + { + thd->no_errors=0; + free_root(&alloc,MYF(0)); // Return memory & allocator + DBUG_RETURN(-1); // Error + } + key_parts= param.key_parts; + + /* + Make an array with description of all key parts of all table keys. + This is used in get_mm_parts function. + */ + key_info= head->key_info; + uint max_key_len= 0; + + Json_writer_array trace_idx(thd, "potential_range_indexes"); + + for (idx=0 ; idx < head->s->keys ; idx++, key_info++) + { + Json_writer_object trace_idx_details(thd); + trace_idx_details.add("index", key_info->name); + KEY_PART_INFO *key_part_info; + uint n_key_parts= head->actual_n_key_parts(key_info); + + if (!keys_to_use.is_set(idx)) + { + trace_idx_details.add("usable", false) + .add("cause", "not applicable"); + continue; + } + if (key_info->flags & HA_FULLTEXT) + { + trace_idx_details.add("usable", false).add("cause", "fulltext"); + continue; // ToDo: ft-keys in non-ft ranges, if possible SerG + } + + trace_idx_details.add("usable", true); + param.key[param.keys]=key_parts; + key_part_info= key_info->key_part; + uint cur_key_len= 0; + Json_writer_array trace_keypart(thd, "key_parts"); + for (uint part= 0 ; part < n_key_parts ; + part++, key_parts++, key_part_info++) + { + key_parts->key= param.keys; + key_parts->part= part; + key_parts->length= key_part_info->length; + key_parts->store_length= key_part_info->store_length; + cur_key_len += key_part_info->store_length; + key_parts->field= key_part_info->field; + key_parts->null_bit= key_part_info->null_bit; + key_parts->image_type = + (key_info->flags & HA_SPATIAL) ? Field::itMBR : Field::itRAW; + /* Only HA_PART_KEY_SEG is used */ + key_parts->flag= (uint8) key_part_info->key_part_flag; + trace_keypart.add(key_parts->field->field_name); + } + param.real_keynr[param.keys++]=idx; + if (cur_key_len > max_key_len) + max_key_len= cur_key_len; + } + trace_idx.end(); + + param.key_parts_end=key_parts; + param.alloced_sel_args= 0; + + max_key_len++; /* Take into account the "+1" in QUICK_RANGE::QUICK_RANGE */ + if (!(param.min_key= (uchar*)alloc_root(&alloc,max_key_len)) || + !(param.max_key= (uchar*)alloc_root(&alloc,max_key_len))) + { + thd->no_errors=0; + free_root(&alloc,MYF(0)); // Return memory & allocator + DBUG_RETURN(-1); // Error + } + + thd->mem_root= &alloc; + /* Calculate cost of full index read for the shortest covering index */ + if (!force_quick_range && !head->covering_keys.is_clear_all()) + { + int key_for_use= find_shortest_key(head, &head->covering_keys); + double key_read_time= (head->file->key_scan_time(key_for_use) + + rows2double(records) / TIME_FOR_COMPARE); + DBUG_PRINT("info", ("'all'+'using index' scan will be using key %d, " + "read time %g", key_for_use, key_read_time)); + + Json_writer_object trace_cov(thd, "best_covering_index_scan"); + bool chosen= FALSE; + if (key_read_time < read_time) + { + read_time= key_read_time; + chosen= TRUE; + } + trace_cov.add("index", head->key_info[key_for_use].name) + .add("cost", key_read_time).add("chosen", chosen); + if (!chosen) + trace_cov.add("cause", "cost"); + } + + double best_read_time= read_time; + + if (notnull_cond) + notnull_cond_tree= notnull_cond->get_mm_tree(¶m, ¬null_cond); + + if (cond || notnull_cond_tree) + { + { + Json_writer_array trace_range_summary(thd, + "setup_range_conditions"); + if (cond) + tree= cond->get_mm_tree(¶m, &cond); + if (notnull_cond_tree) + tree= tree_and(¶m, tree, notnull_cond_tree); + } + if (tree) + { + if (tree->type == SEL_TREE::IMPOSSIBLE) + { + records=0L; /* Return -1 from this function. */ + read_time= (double) HA_POS_ERROR; + trace_range.add("impossible_range", true); + goto free_mem; + } + /* + If the tree can't be used for range scans, proceed anyway, as we + can construct a group-min-max quick select + */ + if (tree->type != SEL_TREE::KEY && tree->type != SEL_TREE::KEY_SMALLER) + { + trace_range.add("range_scan_possible", false); + tree= NULL; + } + } + else if (thd->is_error()) + { + thd->no_errors=0; + thd->mem_root= param.old_root; + free_root(&alloc, MYF(0)); + DBUG_RETURN(-1); + } + } + + if (tree) + { + /* + It is possible to use a range-based quick select (but it might be + slower than 'all' table scan). + */ + TRP_ROR_INTERSECT *rori_trp; + TRP_INDEX_INTERSECT *intersect_trp; + bool can_build_covering= FALSE; + Json_writer_object trace_range(thd, "analyzing_range_alternatives"); + + backup_keys= (SEL_ARG**) alloca(sizeof(backup_keys[0])*param.keys); + memcpy(&backup_keys[0], &tree->keys[0], + sizeof(backup_keys[0])*param.keys); + + remove_nonrange_trees(¶m, tree); + + /* Get best 'range' plan and prepare data for making other plans */ + if (auto range_trp= get_key_scans_params(¶m, tree, + only_single_index_range_scan, + true, best_read_time)) + { + best_trp= range_trp; + best_read_time= best_trp->read_cost; + } + + /* + Simultaneous key scans and row deletes on several handler + objects are not allowed so don't use ROR-intersection for + table deletes. + */ + if ((thd->lex->sql_command != SQLCOM_DELETE) && + optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE) && + !only_single_index_range_scan) + { + /* + Get best non-covering ROR-intersection plan and prepare data for + building covering ROR-intersection. + */ + if ((rori_trp= get_best_ror_intersect(¶m, tree, best_read_time, + &can_build_covering))) + { + best_trp= rori_trp; + best_read_time= best_trp->read_cost; + /* + Try constructing covering ROR-intersect only if it looks possible + and worth doing. + */ + if (!rori_trp->is_covering && can_build_covering && + (rori_trp= get_best_covering_ror_intersect(¶m, tree, + best_read_time))) + best_trp= rori_trp; + } + } + /* + Do not look for an index intersection plan if there is a covering + index. The scan by this covering index will be always cheaper than + any index intersection. + */ + if (param.table->covering_keys.is_clear_all() && + optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE) && + optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE_SORT_INTERSECT) && + !only_single_index_range_scan) + { + if ((intersect_trp= get_best_index_intersect(¶m, tree, + best_read_time))) + { + best_trp= intersect_trp; + best_read_time= best_trp->read_cost; + set_if_smaller(param.table->opt_range_condition_rows, + intersect_trp->records); + } + } + + if (optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE) && + head->stat_records() != 0 && !only_single_index_range_scan) + { + /* Try creating index_merge/ROR-union scan. */ + SEL_IMERGE *imerge; + TABLE_READ_PLAN *best_conj_trp= NULL, + *UNINIT_VAR(new_conj_trp); /* no empty index_merge lists possible */ + DBUG_PRINT("info",("No range reads possible," + " trying to construct index_merge")); + List_iterator_fast<SEL_IMERGE> it(tree->merges); + Json_writer_array trace_idx_merge(thd, "analyzing_index_merge_union"); + while ((imerge= it++)) + { + new_conj_trp= get_best_disjunct_quick(¶m, imerge, best_read_time); + if (new_conj_trp) + set_if_smaller(param.table->opt_range_condition_rows, + new_conj_trp->records); + if (new_conj_trp && + (!best_conj_trp || + new_conj_trp->read_cost < best_conj_trp->read_cost)) + { + best_conj_trp= new_conj_trp; + best_read_time= best_conj_trp->read_cost; + } + } + if (best_conj_trp) + best_trp= best_conj_trp; + } + } + + /* + Try to construct a QUICK_GROUP_MIN_MAX_SELECT. + Notice that it can be constructed no matter if there is a range tree. + */ + DBUG_EXECUTE_IF("force_group_by", force_group_by = true; ); + if (!only_single_index_range_scan) + { + TRP_GROUP_MIN_MAX *group_trp; + if (tree) + restore_nonrange_trees(¶m, tree, backup_keys); + if ((group_trp= get_best_group_min_max(¶m, tree, read_time))) + { + param.table->opt_range_condition_rows= MY_MIN(group_trp->records, + head->stat_records()); + Json_writer_object grp_summary(thd, "best_group_range_summary"); + + if (unlikely(thd->trace_started())) + group_trp->trace_basic_info(¶m, &grp_summary); + + if (group_trp->read_cost < best_read_time || force_group_by) + { + grp_summary.add("chosen", true); + best_trp= group_trp; + best_read_time= best_trp->read_cost; + } + else + grp_summary.add("chosen", false).add("cause", "cost"); + } + if (tree) + remove_nonrange_trees(¶m, tree); + } + + thd->mem_root= param.old_root; + + /* If we got a read plan, create a quick select from it. */ + if (best_trp) + { + records= best_trp->records; + if (!(quick= best_trp->make_quick(¶m, TRUE)) || quick->init()) + { + delete quick; + quick= NULL; + } + } + possible_keys= param.possible_keys; + + free_mem: + if (unlikely(quick && best_trp && thd->trace_started())) + { + Json_writer_object trace_range_summary(thd, + "chosen_range_access_summary"); + { + Json_writer_object trace_range_plan(thd, "range_access_plan"); + best_trp->trace_basic_info(¶m, &trace_range_plan); + } + trace_range_summary.add("rows_for_plan", quick->records) + .add("cost_for_plan", quick->read_time) + .add("chosen", true); + } + + free_root(&alloc,MYF(0)); // Return memory & allocator + thd->mem_root= param.old_root; + thd->no_errors=0; + } + + DBUG_EXECUTE("info", print_quick(quick, &needed_reg);); + + /* + Assume that if the user is using 'limit' we will only need to scan + limit rows if we are using a key + */ + DBUG_RETURN(records ? MY_TEST(quick) : -1); +} + +/**************************************************************************** + * Condition selectivity module + ****************************************************************************/ + + +/* + Build descriptors of pseudo-indexes over columns to perform range analysis + + SYNOPSIS + create_key_parts_for_pseudo_indexes() + param IN/OUT data structure for the descriptors to be built + used_fields bitmap of columns for which the descriptors are to be built + + DESCRIPTION + For each column marked in the bitmap used_fields the function builds + a descriptor of a single-component pseudo-index over this column that + can be used for the range analysis of the predicates over this columns. + The descriptors are created in the memory of param->mem_root. + + RETURN + FALSE in the case of success + TRUE otherwise +*/ + +static +bool create_key_parts_for_pseudo_indexes(RANGE_OPT_PARAM *param, + MY_BITMAP *used_fields) +{ + Field **field_ptr; + TABLE *table= param->table; + uint parts= 0; + + for (field_ptr= table->field; *field_ptr; field_ptr++) + { + Field *field= *field_ptr; + if (bitmap_is_set(used_fields, field->field_index) && + is_eits_usable(field)) + parts++; + } + + KEY_PART *key_part; + uint keys= 0; + + if (!parts) + return TRUE; + + if (!(key_part= (KEY_PART *) alloc_root(param->mem_root, + sizeof(KEY_PART) * parts))) + return TRUE; + + param->key_parts= key_part; + uint max_key_len= 0; + for (field_ptr= table->field; *field_ptr; field_ptr++) + { + Field *field= *field_ptr; + if (bitmap_is_set(used_fields, field->field_index)) + { + if (!is_eits_usable(field)) + continue; + + uint16 store_length; + uint16 max_key_part_length= (uint16) table->file->max_key_part_length(); + key_part->key= keys; + key_part->part= 0; + if (field->flags & BLOB_FLAG) + key_part->length= max_key_part_length; + else + { + key_part->length= (uint16) field->key_length(); + set_if_smaller(key_part->length, max_key_part_length); + } + store_length= key_part->length; + if (field->real_maybe_null()) + store_length+= HA_KEY_NULL_LENGTH; + if (field->real_type() == MYSQL_TYPE_VARCHAR) + store_length+= HA_KEY_BLOB_LENGTH; + if (max_key_len < store_length) + max_key_len= store_length; + key_part->store_length= store_length; + key_part->field= field; + key_part->image_type= Field::itRAW; + key_part->flag= 0; + param->key[keys]= key_part; + keys++; + key_part++; + } + } + + max_key_len++; /* Take into account the "+1" in QUICK_RANGE::QUICK_RANGE */ + if (!(param->min_key= (uchar*)alloc_root(param->mem_root, max_key_len)) || + !(param->max_key= (uchar*)alloc_root(param->mem_root, max_key_len))) + { + return true; + } + param->keys= keys; + param->key_parts_end= key_part; + + return FALSE; +} + + +/* + Estimate the number of rows in all ranges built for a column + by the range optimizer + + SYNOPSIS + records_in_column_ranges() + param the data structure to access descriptors of pseudo indexes + built over columns used in the condition of the processed query + idx the index of the descriptor of interest in param + tree the tree representing ranges built for the interesting column + + DESCRIPTION + This function retrieves the ranges represented by the SEL_ARG 'tree' and + for each of them r it calls the function get_column_range_cardinality() + that estimates the number of expected rows in r. It is assumed that param + is the data structure containing the descriptors of pseudo-indexes that + has been built to perform range analysis of the range conditions imposed + on the columns used in the processed query, while idx is the index of the + descriptor created in 'param' exactly for the column for which 'tree' + has been built by the range optimizer. + + RETURN + the number of rows in the retrieved ranges +*/ + +static +double records_in_column_ranges(PARAM *param, uint idx, + SEL_ARG *tree) +{ + THD *thd= param->thd; + SEL_ARG_RANGE_SEQ seq; + KEY_MULTI_RANGE range; + range_seq_t seq_it; + double rows; + Field *field; + uint flags= 0; + double total_rows= 0; + RANGE_SEQ_IF seq_if = {NULL, sel_arg_range_seq_init, + sel_arg_range_seq_next, 0, 0}; + + /* Handle cases when we don't have a valid non-empty list of range */ + if (!tree) + return DBL_MAX; + if (tree->type == SEL_ARG::IMPOSSIBLE) + return (0L); + + field= tree->field; + + seq.keyno= idx; + seq.real_keyno= MAX_KEY; + seq.param= param; + seq.start= tree; + seq.is_ror_scan= FALSE; + + seq_it= seq_if.init((void *) &seq, 0, flags); + + Json_writer_array range_trace(thd, "ranges"); + + while (!seq_if.next(seq_it, &range)) + { + key_range *min_endp, *max_endp; + min_endp= range.start_key.length? &range.start_key : NULL; + max_endp= range.end_key.length? &range.end_key : NULL; + int range_flag= range.range_flag; + + if (!range.start_key.length) + range_flag |= NO_MIN_RANGE; + if (!range.end_key.length) + range_flag |= NO_MAX_RANGE; + if (range.start_key.flag == HA_READ_AFTER_KEY) + range_flag |= NEAR_MIN; + if (range.start_key.flag == HA_READ_BEFORE_KEY) + range_flag |= NEAR_MAX; + + if (unlikely(thd->trace_started())) + { + StringBuffer<128> range_info(system_charset_info); + print_range_for_non_indexed_field(&range_info, field, &range); + range_trace.add(range_info.c_ptr_safe(), range_info.length()); + } + + rows= get_column_range_cardinality(field, min_endp, max_endp, range_flag); + if (DBL_MAX == rows) + { + total_rows= DBL_MAX; + break; + } + total_rows += rows; + } + return total_rows; +} + + +/* + Calculate the selectivity of the condition imposed on the rows of a table + + SYNOPSIS + calculate_cond_selectivity_for_table() + thd the context handle + table the table of interest + cond conditions imposed on the rows of the table + + DESCRIPTION + This function calculates the selectivity of range conditions cond imposed + on the rows of 'table' in the processed query. + The calculated selectivity is assigned to the field table->cond_selectivity. + + Selectivity is calculated as a product of selectivities imposed by: + + 1. possible range accesses. (if multiple range accesses use the same + restrictions on the same field, we make adjustments for that) + 2. Sargable conditions on fields for which we have column statistics (if + a field is used in a possible range access, we assume that selectivity + is already provided by the range access' estimates) + 3. Reading a few records from the table pages and checking the condition + selectivity (this is used for conditions like "column LIKE '%val%'" + where approaches #1 and #2 do not provide selectivity data). + + NOTE + Currently the selectivities of range conditions over different columns are + considered independent. + + RETURN + FALSE on success + TRUE otherwise +*/ + +bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond) +{ + uint keynr; + uint max_quick_key_parts= 0; + MY_BITMAP *used_fields= &table->cond_set; + double table_records= (double)table->stat_records(); + DBUG_ENTER("calculate_cond_selectivity_for_table"); + + table->cond_selectivity= 1.0; + + if (table_records == 0) + DBUG_RETURN(FALSE); + + QUICK_SELECT_I *quick; + if ((quick=table->reginfo.join_tab->quick) && + quick->get_type() == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX) + { + table->cond_selectivity*= (quick->records/table_records); + DBUG_RETURN(FALSE); + } + + if (!*cond) + DBUG_RETURN(FALSE); + + if (table->pos_in_table_list->schema_table) + DBUG_RETURN(FALSE); + + MY_BITMAP handled_columns; + my_bitmap_map* buf; + if (!(buf= (my_bitmap_map*)thd->alloc(table->s->column_bitmap_size))) + DBUG_RETURN(TRUE); + my_bitmap_init(&handled_columns, buf, table->s->fields, FALSE); + + /* + Calculate the selectivity of the range conditions supported by indexes. + + First, take into account possible range accesses. + range access estimates are the most precise, we prefer them to any other + estimate sources. + */ + + Json_writer_object trace_wrapper(thd); + Json_writer_array selectivity_for_indexes(thd, "selectivity_for_indexes"); + + for (keynr= 0; keynr < table->s->keys; keynr++) + { + if (table->opt_range_keys.is_set(keynr)) + set_if_bigger(max_quick_key_parts, table->opt_range[keynr].key_parts); + } + + /* + Walk through all indexes, indexes where range access uses more keyparts + go first. + */ + for (uint quick_key_parts= max_quick_key_parts; + quick_key_parts; quick_key_parts--) + { + for (keynr= 0; keynr < table->s->keys; keynr++) + { + if (table->opt_range_keys.is_set(keynr) && + table->opt_range[keynr].key_parts == quick_key_parts) + { + uint i; + uint used_key_parts= table->opt_range[keynr].key_parts; + double quick_cond_selectivity= (table->opt_range[keynr].rows / + table_records); + KEY *key_info= table->key_info + keynr; + KEY_PART_INFO* key_part= key_info->key_part; + /* + Suppose, there are range conditions on two keys + KEY1 (col1, col2) + KEY2 (col3, col2) + + we don't want to count selectivity of condition on col2 twice. + + First, find the longest key prefix that's made of columns whose + selectivity wasn't already accounted for. + */ + for (i= 0; i < used_key_parts; i++, key_part++) + { + if (bitmap_is_set(&handled_columns, key_part->fieldnr-1)) + break; + bitmap_set_bit(&handled_columns, key_part->fieldnr-1); + } + if (i) + { + double UNINIT_VAR(selectivity_mult); + + /* + There is at least 1-column prefix of columns whose selectivity has + not yet been accounted for. + */ + table->cond_selectivity*= quick_cond_selectivity; + Json_writer_object selectivity_for_index(thd); + selectivity_for_index.add("index_name", key_info->name) + .add("selectivity_from_index", + quick_cond_selectivity); + if (i != used_key_parts) + { + /* + Range access got us estimate for #used_key_parts. + We need estimate for #(i-1) key parts. + */ + double f1= key_info->actual_rec_per_key(i-1); + double f2= key_info->actual_rec_per_key(i); + if (f1 > 0 && f2 > 0) + selectivity_mult= f1 / f2; + else + { + /* + No statistics available, assume the selectivity is proportional + to the number of key parts. + (i=0 means 1 keypart, i=1 means 2 keyparts, so use i+1) + */ + selectivity_mult= ((double)(i+1)) / i; + } + table->cond_selectivity*= selectivity_mult; + selectivity_for_index.add("selectivity_multiplier", + selectivity_mult); + } + /* + We need to set selectivity for fields supported by indexes. + For single-component indexes and for some first components + of other indexes we do it here. For the remaining fields + we do it later in this function, in the same way as for the + fields not used in any indexes. + */ + if (i == 1) + { + uint fieldnr= key_info->key_part[0].fieldnr; + table->field[fieldnr-1]->cond_selectivity= quick_cond_selectivity; + if (i != used_key_parts) + table->field[fieldnr-1]->cond_selectivity*= selectivity_mult; + bitmap_clear_bit(used_fields, fieldnr-1); + } + } + } + } + } + selectivity_for_indexes.end(); + + /* + Second step: calculate the selectivity of the range conditions not + supported by any index and selectivity of the range condition + over the fields whose selectivity has not been set yet. + */ + Json_writer_array selectivity_for_columns(thd, "selectivity_for_columns"); + + if (thd->variables.optimizer_use_condition_selectivity > 2 && + !bitmap_is_clear_all(used_fields) && + thd->variables.use_stat_tables > 0 && table->stats_is_read) + { + PARAM param; + MEM_ROOT alloc; + SEL_TREE *tree; + double rows; + + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + param.thd= thd; + param.mem_root= &alloc; + param.old_root= thd->mem_root; + param.table= table; + param.remove_false_where_parts= true; + + if (create_key_parts_for_pseudo_indexes(¶m, used_fields)) + goto free_alloc; + + param.prev_tables= param.read_tables= 0; + param.current_table= table->map; + param.using_real_indexes= FALSE; + param.real_keynr[0]= 0; + param.alloced_sel_args= 0; + param.max_key_parts= 0; + + thd->no_errors=1; + + tree= cond[0]->get_mm_tree(¶m, cond); + + if (!tree) + goto free_alloc; + + table->reginfo.impossible_range= 0; + if (tree->type == SEL_TREE::IMPOSSIBLE) + { + rows= 0; + table->reginfo.impossible_range= 1; + goto free_alloc; + } + else if (tree->type == SEL_TREE::ALWAYS) + { + rows= table_records; + goto free_alloc; + } + else if (tree->type == SEL_TREE::MAYBE) + { + rows= table_records; + goto free_alloc; + } + + for (uint idx= 0; idx < param.keys; idx++) + { + SEL_ARG *key= tree->keys[idx]; + if (key) + { + Json_writer_object selectivity_for_column(thd); + selectivity_for_column.add("column_name", key->field->field_name); + if (key->type == SEL_ARG::IMPOSSIBLE) + { + rows= 0; + table->reginfo.impossible_range= 1; + selectivity_for_column.add("selectivity_from_histogram", rows); + selectivity_for_column.add("cause", "impossible range"); + goto free_alloc; + } + else + { + rows= records_in_column_ranges(¶m, idx, key); + if (rows != DBL_MAX) + { + key->field->cond_selectivity= rows/table_records; + selectivity_for_column.add("selectivity_from_histogram", + key->field->cond_selectivity); + } + } + } + } + + for (Field **field_ptr= table->field; *field_ptr; field_ptr++) + { + Field *table_field= *field_ptr; + if (bitmap_is_set(used_fields, table_field->field_index) && + table_field->cond_selectivity < 1.0) + { + if (!bitmap_is_set(&handled_columns, table_field->field_index)) + table->cond_selectivity*= table_field->cond_selectivity; + } + } + + free_alloc: + thd->no_errors= 0; + thd->mem_root= param.old_root; + free_root(&alloc, MYF(0)); + + } + selectivity_for_columns.end(); + + if (quick && (quick->get_type() == QUICK_SELECT_I::QS_TYPE_ROR_UNION || + quick->get_type() == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE)) + { + table->cond_selectivity*= (quick->records/table_records); + } + + bitmap_union(used_fields, &handled_columns); + + /* Check if we can improve selectivity estimates by using sampling */ + ulong check_rows= + MY_MIN(thd->variables.optimizer_selectivity_sampling_limit, + (ulong) (table_records * SELECTIVITY_SAMPLING_SHARE)); + if (*cond && check_rows > SELECTIVITY_SAMPLING_THRESHOLD && + thd->variables.optimizer_use_condition_selectivity > 4) + { + find_selective_predicates_list_processor_data *dt= + (find_selective_predicates_list_processor_data *) + alloc_root(thd->mem_root, + sizeof(find_selective_predicates_list_processor_data)); + if (!dt) + DBUG_RETURN(TRUE); + dt->list.empty(); + dt->table= table; + if ((*cond)->walk(&Item::find_selective_predicates_list_processor, 0, dt)) + DBUG_RETURN(TRUE); + if (dt->list.elements > 0) + { + check_rows= check_selectivity(thd, check_rows, table, &dt->list); + if (check_rows > SELECTIVITY_SAMPLING_THRESHOLD) + { + COND_STATISTIC *stat; + List_iterator_fast<COND_STATISTIC> it(dt->list); + double examined_rows= check_rows; + while ((stat= it++)) + { + if (!stat->positive) + { + DBUG_PRINT("info", ("To avoid 0 assigned 1 to the counter")); + stat->positive= 1; // avoid 0 + } + DBUG_PRINT("info", ("The predicate selectivity : %g", + (double)stat->positive / examined_rows)); + double selectivity= ((double)stat->positive) / examined_rows; + table->cond_selectivity*= selectivity; + /* + If a field is involved then we register its selectivity in case + there in an equality with the field. + For example in case + t1.a LIKE "%bla%" and t1.a = t2.b + the selectivity we have found could be used also for t2. + */ + if (stat->field_arg) + { + stat->field_arg->cond_selectivity*= selectivity; + + if (stat->field_arg->next_equal_field) + { + for (Field *next_field= stat->field_arg->next_equal_field; + next_field != stat->field_arg; + next_field= next_field->next_equal_field) + { + next_field->cond_selectivity*= selectivity; + next_field->table->cond_selectivity*= selectivity; + } + } + } + } + + } + /* This list and its elements put to mem_root so should not be freed */ + table->cond_selectivity_sampling_explain= &dt->list; + } + } + trace_wrapper.add("cond_selectivity", table->cond_selectivity); + DBUG_RETURN(FALSE); +} + +/**************************************************************************** + * Condition selectivity code ends + ****************************************************************************/ + +/**************************************************************************** + * Partition pruning module + ****************************************************************************/ + +/* + Store field key image to table record + + SYNOPSIS + store_key_image_to_rec() + field Field which key image should be stored + ptr Field value in key format + len Length of the value, in bytes + + ATTENTION + len is the length of the value not counting the NULL-byte (at the same + time, ptr points to the key image, which starts with NULL-byte for + nullable columns) + + DESCRIPTION + Copy the field value from its key image to the table record. The source + is the value in key image format, occupying len bytes in buffer pointed + by ptr. The destination is table record, in "field value in table record" + format. +*/ + +void store_key_image_to_rec(Field *field, uchar *ptr, uint len) +{ + /* Do the same as print_key() does */ + + if (field->real_maybe_null()) + { + if (*ptr) + { + field->set_null(); + return; + } + field->set_notnull(); + ptr++; + } + MY_BITMAP *old_map= dbug_tmp_use_all_columns(field->table, + &field->table->write_set); + field->set_key_image(ptr, len); + dbug_tmp_restore_column_map(&field->table->write_set, old_map); +} + +#ifdef WITH_PARTITION_STORAGE_ENGINE + +/* + PartitionPruningModule + + This part of the code does partition pruning. Partition pruning solves the + following problem: given a query over partitioned tables, find partitions + that we will not need to access (i.e. partitions that we can assume to be + empty) when executing the query. + The set of partitions to prune doesn't depend on which query execution + plan will be used to execute the query. + + HOW IT WORKS + + Partition pruning module makes use of RangeAnalysisModule. The following + examples show how the problem of partition pruning can be reduced to the + range analysis problem: + + EXAMPLE 1 + Consider a query: + + SELECT * FROM t1 WHERE (t1.a < 5 OR t1.a = 10) AND t1.a > 3 AND t1.b='z' + + where table t1 is partitioned using PARTITION BY RANGE(t1.a). An apparent + way to find the used (i.e. not pruned away) partitions is as follows: + + 1. analyze the WHERE clause and extract the list of intervals over t1.a + for the above query we will get this list: {(3 < t1.a < 5), (t1.a=10)} + + 2. for each interval I + { + find partitions that have non-empty intersection with I; + mark them as used; + } + + EXAMPLE 2 + Suppose the table is partitioned by HASH(part_func(t1.a, t1.b)). Then + we need to: + + 1. Analyze the WHERE clause and get a list of intervals over (t1.a, t1.b). + The list of intervals we'll obtain will look like this: + ((t1.a, t1.b) = (1,'foo')), + ((t1.a, t1.b) = (2,'bar')), + ((t1,a, t1.b) > (10,'zz')) + + 2. for each interval I + { + if (the interval has form "(t1.a, t1.b) = (const1, const2)" ) + { + calculate HASH(part_func(t1.a, t1.b)); + find which partition has records with this hash value and mark + it as used; + } + else + { + mark all partitions as used; + break; + } + } + + For both examples the step #1 is exactly what RangeAnalysisModule could + be used to do, if it was provided with appropriate index description + (array of KEY_PART structures). + In example #1, we need to provide it with description of index(t1.a), + in example #2, we need to provide it with description of index(t1.a, t1.b). + + These index descriptions are further called "partitioning index + descriptions". Note that it doesn't matter if such indexes really exist, + as range analysis module only uses the description. + + Putting it all together, partitioning module works as follows: + + prune_partitions() { + call create_partition_index_description(); + + call get_mm_tree(); // invoke the RangeAnalysisModule + + // analyze the obtained interval list and get used partitions + call find_used_partitions(); + } + +*/ + +struct st_part_prune_param; +struct st_part_opt_info; + +typedef void (*mark_full_part_func)(partition_info*, uint32); + +/* + Partition pruning operation context +*/ +typedef struct st_part_prune_param +{ + RANGE_OPT_PARAM range_param; /* Range analyzer parameters */ + + /*************************************************************** + Following fields are filled in based solely on partitioning + definition and not modified after that: + **************************************************************/ + partition_info *part_info; /* Copy of table->part_info */ + /* Function to get partition id from partitioning fields only */ + get_part_id_func get_top_partition_id_func; + /* Function to mark a partition as used (w/all subpartitions if they exist)*/ + mark_full_part_func mark_full_partition_used; + + /* Partitioning 'index' description, array of key parts */ + KEY_PART *key; + + /* + Number of fields in partitioning 'index' definition created for + partitioning (0 if partitioning 'index' doesn't include partitioning + fields) + */ + uint part_fields; + uint subpart_fields; /* Same as above for subpartitioning */ + + /* + Number of the last partitioning field keypart in the index, or -1 if + partitioning index definition doesn't include partitioning fields. + */ + int last_part_partno; + int last_subpart_partno; /* Same as above for supartitioning */ + + /* + is_part_keypart[i] == MY_TEST(keypart #i in partitioning index is a member + used in partitioning) + Used to maintain current values of cur_part_fields and cur_subpart_fields + */ + my_bool *is_part_keypart; + /* Same as above for subpartitioning */ + my_bool *is_subpart_keypart; + + my_bool ignore_part_fields; /* Ignore rest of partioning fields */ + + /*************************************************************** + Following fields form find_used_partitions() recursion context: + **************************************************************/ + SEL_ARG **arg_stack; /* "Stack" of SEL_ARGs */ + SEL_ARG **arg_stack_end; /* Top of the stack */ + /* Number of partitioning fields for which we have a SEL_ARG* in arg_stack */ + uint cur_part_fields; + /* Same as cur_part_fields, but for subpartitioning */ + uint cur_subpart_fields; + + /* Iterator to be used to obtain the "current" set of used partitions */ + PARTITION_ITERATOR part_iter; + + /* Initialized bitmap of num_subparts size */ + MY_BITMAP subparts_bitmap; + + uchar *cur_min_key; + uchar *cur_max_key; + + uint cur_min_flag, cur_max_flag; +} PART_PRUNE_PARAM; + +static bool create_partition_index_description(PART_PRUNE_PARAM *prune_par); +static int find_used_partitions(PART_PRUNE_PARAM *ppar, SEL_ARG *key_tree); +static int find_used_partitions_imerge(PART_PRUNE_PARAM *ppar, + SEL_IMERGE *imerge); +static int find_used_partitions_imerge_list(PART_PRUNE_PARAM *ppar, + List<SEL_IMERGE> &merges); +static void mark_all_partitions_as_used(partition_info *part_info); + +#ifndef DBUG_OFF +static void print_partitioning_index(KEY_PART *parts, KEY_PART *parts_end); +static void dbug_print_field(Field *field); +static void dbug_print_segment_range(SEL_ARG *arg, KEY_PART *part); +static void dbug_print_singlepoint_range(SEL_ARG **start, uint num); +#endif + + +/** + Perform partition pruning for a given table and condition. + + @param thd Thread handle + @param table Table to perform partition pruning for + @param pprune_cond Condition to use for partition pruning + + @note This function assumes that lock_partitions are setup when it + is invoked. The function analyzes the condition, finds partitions that + need to be used to retrieve the records that match the condition, and + marks them as used by setting appropriate bit in part_info->read_partitions + In the worst case all partitions are marked as used. If the table is not + yet locked, it will also unset bits in part_info->lock_partitions that is + not set in read_partitions. + + This function returns promptly if called for non-partitioned table. + + @return Operation status + @retval true Failure + @retval false Success +*/ + +bool prune_partitions(THD *thd, TABLE *table, Item *pprune_cond) +{ + bool retval= FALSE; + partition_info *part_info = table->part_info; + DBUG_ENTER("prune_partitions"); + + if (!part_info) + DBUG_RETURN(FALSE); /* not a partitioned table */ + + if (!pprune_cond) + { + mark_all_partitions_as_used(part_info); + DBUG_RETURN(FALSE); + } + + PART_PRUNE_PARAM prune_param; + MEM_ROOT alloc; + RANGE_OPT_PARAM *range_par= &prune_param.range_param; + MY_BITMAP *old_sets[2]; + + prune_param.part_info= part_info; + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + range_par->mem_root= &alloc; + range_par->old_root= thd->mem_root; + + if (create_partition_index_description(&prune_param)) + { + mark_all_partitions_as_used(part_info); + free_root(&alloc,MYF(0)); // Return memory & allocator + DBUG_RETURN(FALSE); + } + + dbug_tmp_use_all_columns(table, old_sets, + &table->read_set, &table->write_set); + range_par->thd= thd; + range_par->table= table; + /* range_par->cond doesn't need initialization */ + range_par->prev_tables= range_par->read_tables= 0; + range_par->current_table= table->map; + /* It should be possible to switch the following ON: */ + range_par->remove_false_where_parts= false; + + range_par->keys= 1; // one index + range_par->using_real_indexes= FALSE; + range_par->remove_jump_scans= FALSE; + range_par->real_keynr[0]= 0; + range_par->alloced_sel_args= 0; + + thd->no_errors=1; // Don't warn about NULL + thd->mem_root=&alloc; + + bitmap_clear_all(&part_info->read_partitions); + + prune_param.key= prune_param.range_param.key_parts; + SEL_TREE *tree; + int res; + + tree= pprune_cond->get_mm_tree(range_par, &pprune_cond); + if (!tree) + goto all_used; + + if (tree->type == SEL_TREE::IMPOSSIBLE) + { + retval= TRUE; + goto end; + } + + if (tree->type != SEL_TREE::KEY && tree->type != SEL_TREE::KEY_SMALLER) + goto all_used; + + if (tree->merges.is_empty()) + { + /* Range analysis has produced a single list of intervals. */ + prune_param.arg_stack_end= prune_param.arg_stack; + prune_param.cur_part_fields= 0; + prune_param.cur_subpart_fields= 0; + + prune_param.cur_min_key= prune_param.range_param.min_key; + prune_param.cur_max_key= prune_param.range_param.max_key; + prune_param.cur_min_flag= prune_param.cur_max_flag= 0; + + init_all_partitions_iterator(part_info, &prune_param.part_iter); + if (!tree->keys[0] || (-1 == (res= find_used_partitions(&prune_param, + tree->keys[0])))) + goto all_used; + } + else + { + if (tree->merges.elements == 1) + { + /* + Range analysis has produced a "merge" of several intervals lists, a + SEL_TREE that represents an expression in form + sel_imerge = (tree1 OR tree2 OR ... OR treeN) + that cannot be reduced to one tree. This can only happen when + partitioning index has several keyparts and the condition is OR of + conditions that refer to different key parts. For example, we'll get + here for "partitioning_field=const1 OR subpartitioning_field=const2" + */ + if (-1 == (res= find_used_partitions_imerge(&prune_param, + tree->merges.head()))) + goto all_used; + } + else + { + /* + Range analysis has produced a list of several imerges, i.e. a + structure that represents a condition in form + imerge_list= (sel_imerge1 AND sel_imerge2 AND ... AND sel_imergeN) + This is produced for complicated WHERE clauses that range analyzer + can't really analyze properly. + */ + if (-1 == (res= find_used_partitions_imerge_list(&prune_param, + tree->merges))) + goto all_used; + } + } + + /* + res == 0 => no used partitions => retval=TRUE + res == 1 => some used partitions => retval=FALSE + res == -1 - we jump over this line to all_used: + */ + retval= MY_TEST(!res); + goto end; + +all_used: + retval= FALSE; // some partitions are used + mark_all_partitions_as_used(prune_param.part_info); +end: + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); + thd->no_errors=0; + thd->mem_root= range_par->old_root; + free_root(&alloc,MYF(0)); // Return memory & allocator + /* + Must be a subset of the locked partitions. + lock_partitions contains the partitions marked by explicit partition + selection (... t PARTITION (pX) ...) and we must only use partitions + within that set. + */ + bitmap_intersect(&prune_param.part_info->read_partitions, + &prune_param.part_info->lock_partitions); + /* + If not yet locked, also prune partitions to lock if not UPDATEing + partition key fields. This will also prune lock_partitions if we are under + LOCK TABLES, so prune away calls to start_stmt(). + TODO: enhance this prune locking to also allow pruning of + 'UPDATE t SET part_key = const WHERE cond_is_prunable' so it adds + a lock for part_key partition. + */ + if (table->file->get_lock_type() == F_UNLCK && + !partition_key_modified(table, table->write_set)) + { + bitmap_copy(&prune_param.part_info->lock_partitions, + &prune_param.part_info->read_partitions); + } + if (bitmap_is_clear_all(&(prune_param.part_info->read_partitions))) + { + table->all_partitions_pruned_away= true; + retval= TRUE; + } + DBUG_RETURN(retval); +} + + +/* + For SEL_ARG* array, store sel_arg->min values into table record buffer + + SYNOPSIS + store_selargs_to_rec() + ppar Partition pruning context + start Array of SEL_ARG* for which the minimum values should be stored + num Number of elements in the array + + DESCRIPTION + For each SEL_ARG* interval in the specified array, store the left edge + field value (sel_arg->min, key image format) into the table record. +*/ + +static void store_selargs_to_rec(PART_PRUNE_PARAM *ppar, SEL_ARG **start, + int num) +{ + KEY_PART *parts= ppar->range_param.key_parts; + for (SEL_ARG **end= start + num; start != end; start++) + { + SEL_ARG *sel_arg= (*start); + store_key_image_to_rec(sel_arg->field, sel_arg->min_value, + parts[sel_arg->part].length); + } +} + + +/* Mark a partition as used in the case when there are no subpartitions */ +static void mark_full_partition_used_no_parts(partition_info* part_info, + uint32 part_id) +{ + DBUG_ENTER("mark_full_partition_used_no_parts"); + DBUG_PRINT("enter", ("Mark partition %u as used", part_id)); + bitmap_set_bit(&part_info->read_partitions, part_id); + DBUG_VOID_RETURN; +} + + +/* Mark a partition as used in the case when there are subpartitions */ +static void mark_full_partition_used_with_parts(partition_info *part_info, + uint32 part_id) +{ + uint32 start= part_id * part_info->num_subparts; + uint32 end= start + part_info->num_subparts; + DBUG_ENTER("mark_full_partition_used_with_parts"); + + for (; start != end; start++) + { + DBUG_PRINT("info", ("1:Mark subpartition %u as used", start)); + bitmap_set_bit(&part_info->read_partitions, start); + } + DBUG_VOID_RETURN; +} + +/* + Find the set of used partitions for List<SEL_IMERGE> + SYNOPSIS + find_used_partitions_imerge_list + ppar Partition pruning context. + key_tree Intervals tree to perform pruning for. + + DESCRIPTION + List<SEL_IMERGE> represents "imerge1 AND imerge2 AND ...". + The set of used partitions is an intersection of used partitions sets + for imerge_{i}. + We accumulate this intersection in a separate bitmap. + + RETURN + See find_used_partitions() +*/ + +static int find_used_partitions_imerge_list(PART_PRUNE_PARAM *ppar, + List<SEL_IMERGE> &merges) +{ + MY_BITMAP all_merges; + uint bitmap_bytes; + my_bitmap_map *bitmap_buf; + uint n_bits= ppar->part_info->read_partitions.n_bits; + bitmap_bytes= bitmap_buffer_size(n_bits); + if (!(bitmap_buf= (my_bitmap_map*) alloc_root(ppar->range_param.mem_root, + bitmap_bytes))) + { + /* + Fallback, process just the first SEL_IMERGE. This can leave us with more + partitions marked as used then actually needed. + */ + return find_used_partitions_imerge(ppar, merges.head()); + } + my_bitmap_init(&all_merges, bitmap_buf, n_bits, FALSE); + bitmap_set_prefix(&all_merges, n_bits); + + List_iterator<SEL_IMERGE> it(merges); + SEL_IMERGE *imerge; + while ((imerge=it++)) + { + int res= find_used_partitions_imerge(ppar, imerge); + if (!res) + { + /* no used partitions on one ANDed imerge => no used partitions at all */ + return 0; + } + + if (res != -1) + bitmap_intersect(&all_merges, &ppar->part_info->read_partitions); + + + if (bitmap_is_clear_all(&all_merges)) + return 0; + + bitmap_clear_all(&ppar->part_info->read_partitions); + } + memcpy(ppar->part_info->read_partitions.bitmap, all_merges.bitmap, + bitmap_bytes); + return 1; +} + + +/* + Find the set of used partitions for SEL_IMERGE structure + SYNOPSIS + find_used_partitions_imerge() + ppar Partition pruning context. + key_tree Intervals tree to perform pruning for. + + DESCRIPTION + SEL_IMERGE represents "tree1 OR tree2 OR ...". The implementation is + trivial - just use mark used partitions for each tree and bail out early + if for some tree_{i} all partitions are used. + + RETURN + See find_used_partitions(). +*/ + +static +int find_used_partitions_imerge(PART_PRUNE_PARAM *ppar, SEL_IMERGE *imerge) +{ + int res= 0; + for (SEL_TREE **ptree= imerge->trees; ptree < imerge->trees_next; ptree++) + { + ppar->arg_stack_end= ppar->arg_stack; + ppar->cur_part_fields= 0; + ppar->cur_subpart_fields= 0; + + ppar->cur_min_key= ppar->range_param.min_key; + ppar->cur_max_key= ppar->range_param.max_key; + ppar->cur_min_flag= ppar->cur_max_flag= 0; + + init_all_partitions_iterator(ppar->part_info, &ppar->part_iter); + SEL_ARG *key_tree= (*ptree)->keys[0]; + if (!key_tree || (-1 == (res |= find_used_partitions(ppar, key_tree)))) + return -1; + } + return res; +} + + +/* + Collect partitioning ranges for the SEL_ARG tree and mark partitions as used + + SYNOPSIS + find_used_partitions() + ppar Partition pruning context. + key_tree SEL_ARG range tree to perform pruning for + + DESCRIPTION + This function + * recursively walks the SEL_ARG* tree collecting partitioning "intervals" + * finds the partitions one needs to use to get rows in these intervals + * marks these partitions as used. + The next session desribes the process in greater detail. + + IMPLEMENTATION + TYPES OF RESTRICTIONS THAT WE CAN OBTAIN PARTITIONS FOR + We can find out which [sub]partitions to use if we obtain restrictions on + [sub]partitioning fields in the following form: + 1. "partition_field1=const1 AND ... AND partition_fieldN=constN" + 1.1 Same as (1) but for subpartition fields + + If partitioning supports interval analysis (i.e. partitioning is a + function of a single table field, and partition_info:: + get_part_iter_for_interval != NULL), then we can also use condition in + this form: + 2. "const1 <=? partition_field <=? const2" + 2.1 Same as (2) but for subpartition_field + + INFERRING THE RESTRICTIONS FROM SEL_ARG TREE + + The below is an example of what SEL_ARG tree may represent: + + (start) + | $ + | Partitioning keyparts $ subpartitioning keyparts + | $ + | ... ... $ + | | | $ + | +---------+ +---------+ $ +-----------+ +-----------+ + \-| par1=c1 |--| par2=c2 |-----| subpar1=c3|--| subpar2=c5| + +---------+ +---------+ $ +-----------+ +-----------+ + | $ | | + | $ | +-----------+ + | $ | | subpar2=c6| + | $ | +-----------+ + | $ | + | $ +-----------+ +-----------+ + | $ | subpar1=c4|--| subpar2=c8| + | $ +-----------+ +-----------+ + | $ + | $ + +---------+ $ +------------+ +------------+ + | par1=c2 |------------------| subpar1=c10|--| subpar2=c12| + +---------+ $ +------------+ +------------+ + | $ + ... $ + + The up-down connections are connections via SEL_ARG::left and + SEL_ARG::right. A horizontal connection to the right is the + SEL_ARG::next_key_part connection. + + find_used_partitions() traverses the entire tree via recursion on + * SEL_ARG::next_key_part (from left to right on the picture) + * SEL_ARG::left|right (up/down on the pic). Left-right recursion is + performed for each depth level. + + Recursion descent on SEL_ARG::next_key_part is used to accumulate (in + ppar->arg_stack) constraints on partitioning and subpartitioning fields. + For the example in the above picture, one of stack states is: + in find_used_partitions(key_tree = "subpar2=c5") (***) + in find_used_partitions(key_tree = "subpar1=c3") + in find_used_partitions(key_tree = "par2=c2") (**) + in find_used_partitions(key_tree = "par1=c1") + in prune_partitions(...) + We apply partitioning limits as soon as possible, e.g. when we reach the + depth (**), we find which partition(s) correspond to "par1=c1 AND par2=c2", + and save them in ppar->part_iter. + When we reach the depth (***), we find which subpartition(s) correspond to + "subpar1=c3 AND subpar2=c5", and then mark appropriate subpartitions in + appropriate subpartitions as used. + + It is possible that constraints on some partitioning fields are missing. + For the above example, consider this stack state: + in find_used_partitions(key_tree = "subpar2=c12") (***) + in find_used_partitions(key_tree = "subpar1=c10") + in find_used_partitions(key_tree = "par1=c2") + in prune_partitions(...) + Here we don't have constraints for all partitioning fields. Since we've + never set the ppar->part_iter to contain used set of partitions, we use + its default "all partitions" value. We get subpartition id for + "subpar1=c3 AND subpar2=c5", and mark that subpartition as used in every + partition. + + The inverse is also possible: we may get constraints on partitioning + fields, but not constraints on subpartitioning fields. In that case, + calls to find_used_partitions() with depth below (**) will return -1, + and we will mark entire partition as used. + + TODO + Replace recursion on SEL_ARG::left and SEL_ARG::right with a loop + + RETURN + 1 OK, one or more [sub]partitions are marked as used. + 0 The passed condition doesn't match any partitions + -1 Couldn't infer any partition pruning "intervals" from the passed + SEL_ARG* tree (which means that all partitions should be marked as + used) Marking partitions as used is the responsibility of the caller. +*/ + +static +int find_used_partitions(PART_PRUNE_PARAM *ppar, SEL_ARG *key_tree) +{ + int res, left_res=0, right_res=0; + int key_tree_part= (int)key_tree->part; + bool set_full_part_if_bad_ret= FALSE; + bool ignore_part_fields= ppar->ignore_part_fields; + bool did_set_ignore_part_fields= FALSE; + RANGE_OPT_PARAM *range_par= &(ppar->range_param); + + if (check_stack_overrun(range_par->thd, 3*STACK_MIN_SIZE, NULL)) + return -1; + + if (key_tree->left != &null_element) + { + if (-1 == (left_res= find_used_partitions(ppar,key_tree->left))) + return -1; + } + + /* Push SEL_ARG's to stack to enable looking backwards as well */ + ppar->cur_part_fields+= ppar->is_part_keypart[key_tree_part]; + ppar->cur_subpart_fields+= ppar->is_subpart_keypart[key_tree_part]; + *(ppar->arg_stack_end++)= key_tree; + + if (ignore_part_fields) + { + /* + We come here when a condition on the first partitioning + fields led to evaluating the partitioning condition + (due to finding a condition of the type a < const or + b > const). Thus we must ignore the rest of the + partitioning fields but we still want to analyse the + subpartitioning fields. + */ + if (key_tree->next_key_part) + res= find_used_partitions(ppar, key_tree->next_key_part); + else + res= -1; + goto pop_and_go_right; + } + + if (key_tree->type == SEL_ARG::KEY_RANGE) + { + if (ppar->part_info->get_part_iter_for_interval && + key_tree->part <= ppar->last_part_partno) + { + /* Collect left and right bound, their lengths and flags */ + uchar *min_key= ppar->cur_min_key; + uchar *max_key= ppar->cur_max_key; + uchar *tmp_min_key= min_key; + uchar *tmp_max_key= max_key; + key_tree->store_min(ppar->key[key_tree->part].store_length, + &tmp_min_key, ppar->cur_min_flag); + key_tree->store_max(ppar->key[key_tree->part].store_length, + &tmp_max_key, ppar->cur_max_flag); + uint flag; + if (key_tree->next_key_part && + key_tree->next_key_part->part == key_tree->part+1 && + key_tree->next_key_part->part <= ppar->last_part_partno && + key_tree->next_key_part->type == SEL_ARG::KEY_RANGE) + { + /* + There are more key parts for partition pruning to handle + This mainly happens when the condition is an equality + condition. + */ + if ((tmp_min_key - min_key) == (tmp_max_key - max_key) && + (memcmp(min_key, max_key, (uint)(tmp_max_key - max_key)) == 0) && + !key_tree->min_flag && !key_tree->max_flag) + { + /* Set 'parameters' */ + ppar->cur_min_key= tmp_min_key; + ppar->cur_max_key= tmp_max_key; + uint save_min_flag= ppar->cur_min_flag; + uint save_max_flag= ppar->cur_max_flag; + + ppar->cur_min_flag|= key_tree->min_flag; + ppar->cur_max_flag|= key_tree->max_flag; + + res= find_used_partitions(ppar, key_tree->next_key_part); + + /* Restore 'parameters' back */ + ppar->cur_min_key= min_key; + ppar->cur_max_key= max_key; + + ppar->cur_min_flag= save_min_flag; + ppar->cur_max_flag= save_max_flag; + goto pop_and_go_right; + } + /* We have arrived at the last field in the partition pruning */ + uint tmp_min_flag= key_tree->min_flag, + tmp_max_flag= key_tree->max_flag; + if (!tmp_min_flag) + key_tree->next_key_part->store_min_key(ppar->key, + &tmp_min_key, + &tmp_min_flag, + ppar->last_part_partno); + if (!tmp_max_flag) + key_tree->next_key_part->store_max_key(ppar->key, + &tmp_max_key, + &tmp_max_flag, + ppar->last_part_partno); + flag= tmp_min_flag | tmp_max_flag; + } + else + flag= key_tree->min_flag | key_tree->max_flag; + + if (tmp_min_key != range_par->min_key) + flag&= ~NO_MIN_RANGE; + else + flag|= NO_MIN_RANGE; + if (tmp_max_key != range_par->max_key) + flag&= ~NO_MAX_RANGE; + else + flag|= NO_MAX_RANGE; + + /* + We need to call the interval mapper if we have a condition which + makes sense to prune on. In the example of COLUMNS on a and + b it makes sense if we have a condition on a, or conditions on + both a and b. If we only have conditions on b it might make sense + but this is a harder case we will solve later. For the harder case + this clause then turns into use of all partitions and thus we + simply set res= -1 as if the mapper had returned that. + TODO: What to do here is defined in WL#4065. + */ + if (ppar->arg_stack[0]->part == 0 || ppar->part_info->part_type == VERSIONING_PARTITION) + { + uint32 i; + uint32 store_length_array[MAX_KEY]; + uint32 num_keys= ppar->part_fields; + + for (i= 0; i < num_keys; i++) + store_length_array[i]= ppar->key[i].store_length; + res= ppar->part_info-> + get_part_iter_for_interval(ppar->part_info, + FALSE, + store_length_array, + range_par->min_key, + range_par->max_key, + (uint)(tmp_min_key - range_par->min_key), + (uint)(tmp_max_key - range_par->max_key), + flag, + &ppar->part_iter); + if (!res) + goto pop_and_go_right; /* res==0 --> no satisfying partitions */ + } + else + res= -1; + + if (res == -1) + { + /* get a full range iterator */ + init_all_partitions_iterator(ppar->part_info, &ppar->part_iter); + } + /* + Save our intent to mark full partition as used if we will not be able + to obtain further limits on subpartitions + */ + if (key_tree_part < ppar->last_part_partno) + { + /* + We need to ignore the rest of the partitioning fields in all + evaluations after this + */ + did_set_ignore_part_fields= TRUE; + ppar->ignore_part_fields= TRUE; + } + set_full_part_if_bad_ret= TRUE; + goto process_next_key_part; + } + + if (key_tree_part == ppar->last_subpart_partno && + (NULL != ppar->part_info->get_subpart_iter_for_interval)) + { + PARTITION_ITERATOR subpart_iter; + DBUG_EXECUTE("info", dbug_print_segment_range(key_tree, + range_par->key_parts);); + res= ppar->part_info-> + get_subpart_iter_for_interval(ppar->part_info, + TRUE, + NULL, /* Currently not used here */ + key_tree->min_value, + key_tree->max_value, + 0, 0, /* Those are ignored here */ + key_tree->min_flag | + key_tree->max_flag, + &subpart_iter); + if (res == 0) + { + /* + The only case where we can get "no satisfying subpartitions" + returned from the above call is when an error has occurred. + */ + DBUG_ASSERT(range_par->thd->is_error()); + return 0; + } + + if (res == -1) + goto pop_and_go_right; /* all subpartitions satisfy */ + + uint32 subpart_id; + bitmap_clear_all(&ppar->subparts_bitmap); + while ((subpart_id= subpart_iter.get_next(&subpart_iter)) != + NOT_A_PARTITION_ID) + bitmap_set_bit(&ppar->subparts_bitmap, subpart_id); + + /* Mark each partition as used in each subpartition. */ + uint32 part_id; + while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) != + NOT_A_PARTITION_ID) + { + for (uint i= 0; i < ppar->part_info->num_subparts; i++) + if (bitmap_is_set(&ppar->subparts_bitmap, i)) + bitmap_set_bit(&ppar->part_info->read_partitions, + part_id * ppar->part_info->num_subparts + i); + } + goto pop_and_go_right; + } + + if (key_tree->is_singlepoint()) + { + if (key_tree_part == ppar->last_part_partno && + ppar->cur_part_fields == ppar->part_fields && + ppar->part_info->get_part_iter_for_interval == NULL) + { + /* + Ok, we've got "fieldN<=>constN"-type SEL_ARGs for all partitioning + fields. Save all constN constants into table record buffer. + */ + store_selargs_to_rec(ppar, ppar->arg_stack, ppar->part_fields); + DBUG_EXECUTE("info", dbug_print_singlepoint_range(ppar->arg_stack, + ppar->part_fields);); + uint32 part_id; + longlong func_value; + /* Find in which partition the {const1, ...,constN} tuple goes */ + if (ppar->get_top_partition_id_func(ppar->part_info, &part_id, + &func_value)) + { + res= 0; /* No satisfying partitions */ + goto pop_and_go_right; + } + /* Rembember the limit we got - single partition #part_id */ + init_single_partition_iterator(part_id, &ppar->part_iter); + + /* + If there are no subpartitions/we fail to get any limit for them, + then we'll mark full partition as used. + */ + set_full_part_if_bad_ret= TRUE; + goto process_next_key_part; + } + + if (key_tree_part == ppar->last_subpart_partno && + ppar->cur_subpart_fields == ppar->subpart_fields) + { + /* + Ok, we've got "fieldN<=>constN"-type SEL_ARGs for all subpartitioning + fields. Save all constN constants into table record buffer. + */ + store_selargs_to_rec(ppar, ppar->arg_stack_end - ppar->subpart_fields, + ppar->subpart_fields); + DBUG_EXECUTE("info", dbug_print_singlepoint_range(ppar->arg_stack_end- + ppar->subpart_fields, + ppar->subpart_fields);); + /* Find the subpartition (it's HASH/KEY so we always have one) */ + partition_info *part_info= ppar->part_info; + uint32 part_id, subpart_id; + + if (part_info->get_subpartition_id(part_info, &subpart_id)) + return 0; + + /* Mark this partition as used in each subpartition. */ + while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) != + NOT_A_PARTITION_ID) + { + bitmap_set_bit(&part_info->read_partitions, + part_id * part_info->num_subparts + subpart_id); + } + res= 1; /* Some partitions were marked as used */ + goto pop_and_go_right; + } + } + else + { + /* + Can't handle condition on current key part. If we're that deep that + we're processing subpartititoning's key parts, this means we'll not be + able to infer any suitable condition, so bail out. + */ + if (key_tree_part >= ppar->last_part_partno) + { + res= -1; + goto pop_and_go_right; + } + /* + No meaning in continuing with rest of partitioning key parts. + Will try to continue with subpartitioning key parts. + */ + ppar->ignore_part_fields= true; + did_set_ignore_part_fields= true; + goto process_next_key_part; + } + } + +process_next_key_part: + if (key_tree->next_key_part) + res= find_used_partitions(ppar, key_tree->next_key_part); + else + res= -1; + + if (did_set_ignore_part_fields) + { + /* + We have returned from processing all key trees linked to our next + key part. We are ready to be moving down (using right pointers) and + this tree is a new evaluation requiring its own decision on whether + to ignore partitioning fields. + */ + ppar->ignore_part_fields= FALSE; + } + if (set_full_part_if_bad_ret) + { + if (res == -1) + { + /* Got "full range" for subpartitioning fields */ + uint32 part_id; + bool found= FALSE; + while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) != + NOT_A_PARTITION_ID) + { + ppar->mark_full_partition_used(ppar->part_info, part_id); + found= TRUE; + } + res= MY_TEST(found); + } + /* + Restore the "used partitions iterator" to the default setting that + specifies iteration over all partitions. + */ + init_all_partitions_iterator(ppar->part_info, &ppar->part_iter); + } + +pop_and_go_right: + /* Pop this key part info off the "stack" */ + ppar->arg_stack_end--; + ppar->cur_part_fields-= ppar->is_part_keypart[key_tree_part]; + ppar->cur_subpart_fields-= ppar->is_subpart_keypart[key_tree_part]; + + if (res == -1) + return -1; + if (key_tree->right != &null_element) + { + if (-1 == (right_res= find_used_partitions(ppar,key_tree->right))) + return -1; + } + return (left_res || right_res || res); +} + + +static void mark_all_partitions_as_used(partition_info *part_info) +{ + bitmap_copy(&(part_info->read_partitions), + &(part_info->lock_partitions)); +} + + +/* + Check if field types allow to construct partitioning index description + + SYNOPSIS + fields_ok_for_partition_index() + pfield NULL-terminated array of pointers to fields. + + DESCRIPTION + For an array of fields, check if we can use all of the fields to create + partitioning index description. + + We can't process GEOMETRY fields - for these fields singlepoint intervals + cant be generated, and non-singlepoint are "special" kinds of intervals + to which our processing logic can't be applied. + + It is not known if we could process ENUM fields, so they are disabled to be + on the safe side. + + RETURN + TRUE Yes, fields can be used in partitioning index + FALSE Otherwise +*/ + +static bool fields_ok_for_partition_index(Field **pfield) +{ + if (!pfield) + return FALSE; + for (; (*pfield); pfield++) + { + enum_field_types ftype= (*pfield)->real_type(); + if (ftype == MYSQL_TYPE_ENUM || ftype == MYSQL_TYPE_GEOMETRY) + return FALSE; + } + return TRUE; +} + + +/* + Create partition index description and fill related info in the context + struct + + SYNOPSIS + create_partition_index_description() + prune_par INOUT Partition pruning context + + DESCRIPTION + Create partition index description. Partition index description is: + + part_index(used_fields_list(part_expr), used_fields_list(subpart_expr)) + + If partitioning/sub-partitioning uses BLOB or Geometry fields, then + corresponding fields_list(...) is not included into index description + and we don't perform partition pruning for partitions/subpartitions. + + RETURN + TRUE Out of memory or can't do partition pruning at all + FALSE OK +*/ + +static bool create_partition_index_description(PART_PRUNE_PARAM *ppar) +{ + RANGE_OPT_PARAM *range_par= &(ppar->range_param); + partition_info *part_info= ppar->part_info; + uint used_part_fields, used_subpart_fields; + + used_part_fields= fields_ok_for_partition_index(part_info->part_field_array) ? + part_info->num_part_fields : 0; + used_subpart_fields= + fields_ok_for_partition_index(part_info->subpart_field_array)? + part_info->num_subpart_fields : 0; + + uint total_parts= used_part_fields + used_subpart_fields; + + ppar->ignore_part_fields= FALSE; + ppar->part_fields= used_part_fields; + ppar->last_part_partno= (int)used_part_fields - 1; + + ppar->subpart_fields= used_subpart_fields; + ppar->last_subpart_partno= + used_subpart_fields?(int)(used_part_fields + used_subpart_fields - 1): -1; + + if (part_info->is_sub_partitioned()) + { + ppar->mark_full_partition_used= mark_full_partition_used_with_parts; + ppar->get_top_partition_id_func= part_info->get_part_partition_id; + } + else + { + ppar->mark_full_partition_used= mark_full_partition_used_no_parts; + ppar->get_top_partition_id_func= part_info->get_partition_id; + } + + KEY_PART *key_part; + MEM_ROOT *alloc= range_par->mem_root; + if (!total_parts || + !(key_part= (KEY_PART*)alloc_root(alloc, sizeof(KEY_PART)* + total_parts)) || + !(ppar->arg_stack= (SEL_ARG**)alloc_root(alloc, sizeof(SEL_ARG*)* + total_parts)) || + !(ppar->is_part_keypart= (my_bool*)alloc_root(alloc, sizeof(my_bool)* + total_parts)) || + !(ppar->is_subpart_keypart= (my_bool*)alloc_root(alloc, sizeof(my_bool)* + total_parts))) + return TRUE; + + if (ppar->subpart_fields) + { + my_bitmap_map *buf; + uint32 bufsize= bitmap_buffer_size(ppar->part_info->num_subparts); + if (!(buf= (my_bitmap_map*) alloc_root(alloc, bufsize))) + return TRUE; + my_bitmap_init(&ppar->subparts_bitmap, buf, ppar->part_info->num_subparts, + FALSE); + } + range_par->key_parts= key_part; + Field **field= (ppar->part_fields)? part_info->part_field_array : + part_info->subpart_field_array; + bool in_subpart_fields= FALSE; + uint total_key_len= 0; + for (uint part= 0; part < total_parts; part++, key_part++) + { + key_part->key= 0; + key_part->part= part; + key_part->length= (uint16)(*field)->key_length(); + key_part->store_length= (uint16)get_partition_field_store_length(*field); + total_key_len += key_part->store_length; + + DBUG_PRINT("info", ("part %u length %u store_length %u", part, + key_part->length, key_part->store_length)); + + key_part->field= (*field); + key_part->image_type = Field::itRAW; + /* + We set keypart flag to 0 here as the only HA_PART_KEY_SEG is checked + in the RangeAnalysisModule. + */ + key_part->flag= 0; + /* We don't set key_parts->null_bit as it will not be used */ + + ppar->is_part_keypart[part]= !in_subpart_fields; + ppar->is_subpart_keypart[part]= in_subpart_fields; + + /* + Check if this was last field in this array, in this case we + switch to subpartitioning fields. (This will only happens if + there are subpartitioning fields to cater for). + */ + if (!*(++field)) + { + field= part_info->subpart_field_array; + in_subpart_fields= TRUE; + } + } + range_par->key_parts_end= key_part; + + total_key_len++; /* Take into account the "+1" in QUICK_RANGE::QUICK_RANGE */ + if (!(range_par->min_key= (uchar*)alloc_root(alloc,total_key_len)) || + !(range_par->max_key= (uchar*)alloc_root(alloc,total_key_len))) + { + return true; + } + + DBUG_EXECUTE("info", print_partitioning_index(range_par->key_parts, + range_par->key_parts_end);); + return FALSE; +} + + +#ifndef DBUG_OFF + +static void print_partitioning_index(KEY_PART *parts, KEY_PART *parts_end) +{ + DBUG_ENTER("print_partitioning_index"); + DBUG_LOCK_FILE; + fprintf(DBUG_FILE, "partitioning INDEX("); + for (KEY_PART *p=parts; p != parts_end; p++) + { + fprintf(DBUG_FILE, "%s%s", p==parts?"":" ,", p->field->field_name.str); + } + fputs(");\n", DBUG_FILE); + DBUG_UNLOCK_FILE; + DBUG_VOID_RETURN; +} + +/* Print field value into debug trace, in NULL-aware way. */ +static void dbug_print_field(Field *field) +{ + if (field->is_real_null()) + fprintf(DBUG_FILE, "NULL"); + else + { + char buf[256]; + String str(buf, sizeof(buf), &my_charset_bin); + str.length(0); + String *pstr; + pstr= field->val_str(&str); + fprintf(DBUG_FILE, "'%s'", pstr->c_ptr_safe()); + } +} + + +/* Print a "c1 < keypartX < c2" - type interval into debug trace. */ +static void dbug_print_segment_range(SEL_ARG *arg, KEY_PART *part) +{ + DBUG_ENTER("dbug_print_segment_range"); + DBUG_LOCK_FILE; + if (!(arg->min_flag & NO_MIN_RANGE)) + { + store_key_image_to_rec(part->field, arg->min_value, part->length); + dbug_print_field(part->field); + if (arg->min_flag & NEAR_MIN) + fputs(" < ", DBUG_FILE); + else + fputs(" <= ", DBUG_FILE); + } + + fprintf(DBUG_FILE, "%s", part->field->field_name.str); + + if (!(arg->max_flag & NO_MAX_RANGE)) + { + if (arg->max_flag & NEAR_MAX) + fputs(" < ", DBUG_FILE); + else + fputs(" <= ", DBUG_FILE); + store_key_image_to_rec(part->field, arg->max_value, part->length); + dbug_print_field(part->field); + } + fputs("\n", DBUG_FILE); + DBUG_UNLOCK_FILE; + DBUG_VOID_RETURN; +} + + +/* + Print a singlepoint multi-keypart range interval to debug trace + + SYNOPSIS + dbug_print_singlepoint_range() + start Array of SEL_ARG* ptrs representing conditions on key parts + num Number of elements in the array. + + DESCRIPTION + This function prints a "keypartN=constN AND ... AND keypartK=constK"-type + interval to debug trace. +*/ + +static void dbug_print_singlepoint_range(SEL_ARG **start, uint num) +{ + DBUG_ENTER("dbug_print_singlepoint_range"); + DBUG_LOCK_FILE; + SEL_ARG **end= start + num; + + for (SEL_ARG **arg= start; arg != end; arg++) + { + Field *field= (*arg)->field; + fprintf(DBUG_FILE, "%s%s=", (arg==start)?"":", ", field->field_name.str); + dbug_print_field(field); + } + fputs("\n", DBUG_FILE); + DBUG_UNLOCK_FILE; + DBUG_VOID_RETURN; +} +#endif + +/**************************************************************************** + * Partition pruning code ends + ****************************************************************************/ +#endif + + +/* + Get cost of 'sweep' full records retrieval. + SYNOPSIS + get_sweep_read_cost() + param Parameter from test_quick_select + records # of records to be retrieved + RETURN + cost of sweep +*/ + +double get_sweep_read_cost(const PARAM *param, ha_rows records) +{ + double result; + uint pk= param->table->s->primary_key; + DBUG_ENTER("get_sweep_read_cost"); + if (param->table->file->pk_is_clustering_key(pk) || + param->table->file->stats.block_size == 0 /* HEAP */) + { + /* + We are using the primary key to find the rows. + Calculate the cost for this. + */ + result= param->table->file->read_time(pk, (uint)records, records); + } + else + { + /* + Rows will be retreived with rnd_pos(). Caluclate the expected + cost for this. + */ + double n_blocks= + ceil(ulonglong2double(param->table->file->stats.data_file_length) / + IO_SIZE); + double busy_blocks= + n_blocks * (1.0 - pow(1.0 - 1.0/n_blocks, rows2double(records))); + if (busy_blocks < 1.0) + busy_blocks= 1.0; + DBUG_PRINT("info",("sweep: nblocks: %g, busy_blocks: %g", n_blocks, + busy_blocks)); + /* + Disabled: Bail out if # of blocks to read is bigger than # of blocks in + table data file. + if (max_cost != DBL_MAX && (busy_blocks+index_reads_cost) >= n_blocks) + return 1; + */ + JOIN *join= param->thd->lex->first_select_lex()->join; + if (!join || join->table_count == 1) + { + /* No join, assume reading is done in one 'sweep' */ + result= busy_blocks*(DISK_SEEK_BASE_COST + + DISK_SEEK_PROP_COST*n_blocks/busy_blocks); + } + else + { + /* + Possibly this is a join with source table being non-last table, so + assume that disk seeks are random here. + */ + result= busy_blocks; + } + } + DBUG_PRINT("return",("cost: %g", result)); + DBUG_RETURN(result); +} + + +/* + Get best plan for a SEL_IMERGE disjunctive expression. + SYNOPSIS + get_best_disjunct_quick() + param Parameter from check_quick_select function + imerge Expression to use + read_time Don't create scans with cost > read_time + + NOTES + index_merge cost is calculated as follows: + index_merge_cost = + cost(index_reads) + (see #1) + cost(rowid_to_row_scan) + (see #2) + cost(unique_use) (see #3) + + 1. cost(index_reads) =SUM_i(cost(index_read_i)) + For non-CPK scans, + cost(index_read_i) = {cost of ordinary 'index only' scan} + For CPK scan, + cost(index_read_i) = {cost of non-'index only' scan} + + 2. cost(rowid_to_row_scan) + If table PK is clustered then + cost(rowid_to_row_scan) = + {cost of ordinary clustered PK scan with n_ranges=n_rows} + + Otherwise, we use the following model to calculate costs: + We need to retrieve n_rows rows from file that occupies n_blocks blocks. + We assume that offsets of rows we need are independent variates with + uniform distribution in [0..max_file_offset] range. + + We'll denote block as "busy" if it contains row(s) we need to retrieve + and "empty" if doesn't contain rows we need. + + Probability that a block is empty is (1 - 1/n_blocks)^n_rows (this + applies to any block in file). Let x_i be a variate taking value 1 if + block #i is empty and 0 otherwise. + + Then E(x_i) = (1 - 1/n_blocks)^n_rows; + + E(n_empty_blocks) = E(sum(x_i)) = sum(E(x_i)) = + = n_blocks * ((1 - 1/n_blocks)^n_rows) = + ~= n_blocks * exp(-n_rows/n_blocks). + + E(n_busy_blocks) = n_blocks*(1 - (1 - 1/n_blocks)^n_rows) = + ~= n_blocks * (1 - exp(-n_rows/n_blocks)). + + Average size of "hole" between neighbor non-empty blocks is + E(hole_size) = n_blocks/E(n_busy_blocks). + + The total cost of reading all needed blocks in one "sweep" is: + + E(n_busy_blocks)* + (DISK_SEEK_BASE_COST + DISK_SEEK_PROP_COST*n_blocks/E(n_busy_blocks)). + + 3. Cost of Unique use is calculated in Unique::get_use_cost function. + + ROR-union cost is calculated in the same way index_merge, but instead of + Unique a priority queue is used. + + RETURN + Created read plan + NULL - Out of memory or no read scan could be built. +*/ + +static +TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge, + double read_time) +{ + SEL_TREE **ptree; + TRP_INDEX_MERGE *imerge_trp= NULL; + TRP_RANGE **range_scans; + TRP_RANGE **cur_child; + TRP_RANGE **cpk_scan= NULL; + bool imerge_too_expensive= FALSE; + double imerge_cost= 0.0; + ha_rows cpk_scan_records= 0; + ha_rows non_cpk_scan_records= 0; + bool all_scans_ror_able= TRUE; + bool all_scans_rors= TRUE; + uint unique_calc_buff_size; + TABLE_READ_PLAN **roru_read_plans; + TABLE_READ_PLAN **cur_roru_plan; + double roru_index_costs; + ha_rows roru_total_records; + double roru_intersect_part= 1.0; + size_t n_child_scans; + double limit_read_time= read_time; + THD *thd= param->thd; + DBUG_ENTER("get_best_disjunct_quick"); + DBUG_PRINT("info", ("Full table scan cost: %g", read_time)); + + /* + In every tree of imerge remove SEL_ARG trees that do not make ranges. + If after this removal some SEL_ARG tree becomes empty discard imerge. + */ + for (ptree= imerge->trees; ptree != imerge->trees_next; ptree++) + { + if (remove_nonrange_trees(param, *ptree)) + { + imerge->trees_next= imerge->trees; + break; + } + } + + n_child_scans= imerge->trees_next - imerge->trees; + + if (!n_child_scans) + DBUG_RETURN(NULL); + + if (!(range_scans= (TRP_RANGE**)alloc_root(param->mem_root, + sizeof(TRP_RANGE*)* + n_child_scans))) + DBUG_RETURN(NULL); + + Json_writer_object trace_best_disjunct(thd); + Json_writer_array to_merge(thd, "indexes_to_merge"); + /* + Collect best 'range' scan for each of disjuncts, and, while doing so, + analyze possibility of ROR scans. Also calculate some values needed by + other parts of the code. + */ + for (ptree= imerge->trees, cur_child= range_scans; + ptree != imerge->trees_next; + ptree++, cur_child++) + { + DBUG_EXECUTE("info", print_sel_tree(param, *ptree, &(*ptree)->keys_map, + "tree in SEL_IMERGE");); + Json_writer_object trace_idx(thd); + if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, FALSE, + read_time))) + { + /* + One of index scans in this index_merge is more expensive than entire + table read for another available option. The entire index_merge (and + any possible ROR-union) will be more expensive then, too. We continue + here only to update SQL_SELECT members. + */ + imerge_too_expensive= TRUE; + } + if (imerge_too_expensive) + { + trace_idx.add("chosen", false).add("cause", "cost"); + continue; + } + const uint keynr_in_table= param->real_keynr[(*cur_child)->key_idx]; + imerge_cost += (*cur_child)->read_cost; + all_scans_ror_able &= ((*ptree)->n_ror_scans > 0); + all_scans_rors &= (*cur_child)->is_ror; + if (param->table->file->is_clustering_key(param->real_keynr[(*cur_child)->key_idx])) + { + cpk_scan= cur_child; + cpk_scan_records= (*cur_child)->records; + } + else + non_cpk_scan_records += (*cur_child)->records; + trace_idx.add("index_to_merge", + param->table->key_info[keynr_in_table].name) + .add("cumulated_cost", imerge_cost); + } + + to_merge.end(); + + DBUG_PRINT("info", ("index_merge scans cost %g", imerge_cost)); + trace_best_disjunct.add("cost_of_reading_ranges", imerge_cost); + + if (imerge_too_expensive || (imerge_cost > read_time) || + ((non_cpk_scan_records+cpk_scan_records >= + param->table->stat_records()) && + read_time != DBL_MAX)) + { + /* + Bail out if it is obvious that both index_merge and ROR-union will be + more expensive + */ + DBUG_PRINT("info", ("Sum of index_merge scans is more expensive than " + "full table scan, bailing out")); + trace_best_disjunct.add("chosen", false).add("cause", "cost"); + DBUG_RETURN(NULL); + } + + /* + If all scans happen to be ROR, proceed to generate a ROR-union plan (it's + guaranteed to be cheaper than non-ROR union), unless ROR-unions are + disabled in @@optimizer_switch + */ + if (all_scans_rors && + optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_UNION)) + { + roru_read_plans= (TABLE_READ_PLAN**)range_scans; + trace_best_disjunct.add("use_roworder_union", true) + .add("cause", + "always cheaper than non roworder retrieval"); + goto skip_to_ror_scan; + } + + if (cpk_scan) + { + /* + Add one ROWID comparison for each row retrieved on non-CPK scan. (it + is done in QUICK_RANGE_SELECT::row_in_ranges) + */ + double rid_comp_cost= (rows2double(non_cpk_scan_records) / + TIME_FOR_COMPARE_ROWID); + imerge_cost+= rid_comp_cost; + trace_best_disjunct.add("cost_of_mapping_rowid_in_non_clustered_pk_scan", + rid_comp_cost); + } + + /* Calculate cost(rowid_to_row_scan) */ + { + double sweep_cost= get_sweep_read_cost(param, non_cpk_scan_records); + imerge_cost+= sweep_cost; + trace_best_disjunct.add("cost_sort_rowid_and_read_disk", sweep_cost); + } + DBUG_PRINT("info",("index_merge cost with rowid-to-row scan: %g", + imerge_cost)); + if (imerge_cost > read_time || + !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_SORT_UNION)) + { + trace_best_disjunct.add("use_roworder_index_merge", true); + trace_best_disjunct.add("cause", "cost"); + goto build_ror_index_merge; + } + + /* Add Unique operations cost */ + unique_calc_buff_size= + Unique::get_cost_calc_buff_size((ulong)non_cpk_scan_records, + param->table->file->ref_length, + (size_t)param->thd->variables.sortbuff_size); + if (param->imerge_cost_buff_size < unique_calc_buff_size) + { + if (!(param->imerge_cost_buff= (uint*)alloc_root(param->mem_root, + unique_calc_buff_size))) + DBUG_RETURN(NULL); + param->imerge_cost_buff_size= unique_calc_buff_size; + } + + { + const double dup_removal_cost= Unique::get_use_cost( + param->imerge_cost_buff, (uint)non_cpk_scan_records, + param->table->file->ref_length, + (size_t)param->thd->variables.sortbuff_size, + TIME_FOR_COMPARE_ROWID, + FALSE, NULL); + imerge_cost+= dup_removal_cost; + trace_best_disjunct.add("cost_duplicate_removal", dup_removal_cost) + .add("total_cost", imerge_cost); + } + + DBUG_PRINT("info",("index_merge total cost: %g (wanted: less then %g)", + imerge_cost, read_time)); + if (imerge_cost < read_time) + { + if ((imerge_trp= new (param->mem_root)TRP_INDEX_MERGE)) + { + imerge_trp->read_cost= imerge_cost; + imerge_trp->records= non_cpk_scan_records + cpk_scan_records; + imerge_trp->records= MY_MIN(imerge_trp->records, + param->table->stat_records()); + imerge_trp->range_scans= range_scans; + imerge_trp->range_scans_end= range_scans + n_child_scans; + read_time= imerge_cost; + } + if (imerge_trp) + { + TABLE_READ_PLAN *trp= merge_same_index_scans(param, imerge, imerge_trp, + limit_read_time); + if (trp != imerge_trp) + DBUG_RETURN(trp); + } + } + +build_ror_index_merge: + if (!all_scans_ror_able || + param->thd->lex->sql_command == SQLCOM_DELETE || + !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_UNION)) + DBUG_RETURN(imerge_trp); + + /* Ok, it is possible to build a ROR-union, try it. */ + bool dummy; + if (!(roru_read_plans= + (TABLE_READ_PLAN**)alloc_root(param->mem_root, + sizeof(TABLE_READ_PLAN*)* + n_child_scans))) + DBUG_RETURN(imerge_trp); + +skip_to_ror_scan: + roru_index_costs= 0.0; + roru_total_records= 0; + cur_roru_plan= roru_read_plans; + + Json_writer_array trace_analyze_ror(thd, "analyzing_roworder_scans"); + + /* Find 'best' ROR scan for each of trees in disjunction */ + for (ptree= imerge->trees, cur_child= range_scans; + ptree != imerge->trees_next; + ptree++, cur_child++, cur_roru_plan++) + { + Json_writer_object trp_info(thd); + if (unlikely(thd->trace_started())) + (*cur_child)->trace_basic_info(param, &trp_info); + /* + Assume the best ROR scan is the one that has cheapest full-row-retrieval + scan cost. + Also accumulate index_only scan costs as we'll need them to calculate + overall index_intersection cost. + */ + double cost; + if ((*cur_child)->is_ror) + { + /* Ok, we have index_only cost, now get full rows scan cost */ + cost= param->table->file-> + read_time(param->real_keynr[(*cur_child)->key_idx], 1, + (*cur_child)->records) + + rows2double((*cur_child)->records) / TIME_FOR_COMPARE; + } + else + cost= read_time; + + TABLE_READ_PLAN *prev_plan= *cur_child; + if (!(*cur_roru_plan= get_best_ror_intersect(param, *ptree, cost, + &dummy))) + { + if (prev_plan->is_ror) + *cur_roru_plan= prev_plan; + else + DBUG_RETURN(imerge_trp); + roru_index_costs += (*cur_roru_plan)->read_cost; + } + else + roru_index_costs += + ((TRP_ROR_INTERSECT*)(*cur_roru_plan))->index_scan_costs; + roru_total_records += (*cur_roru_plan)->records; + roru_intersect_part *= (*cur_roru_plan)->records / + param->table->stat_records(); + } + trace_analyze_ror.end(); + /* + rows to retrieve= + SUM(rows_in_scan_i) - table_rows * PROD(rows_in_scan_i / table_rows). + This is valid because index_merge construction guarantees that conditions + in disjunction do not share key parts. + */ + roru_total_records -= (ha_rows)(roru_intersect_part* + param->table->stat_records()); + /* ok, got a ROR read plan for each of the disjuncts + Calculate cost: + cost(index_union_scan(scan_1, ... scan_n)) = + SUM_i(cost_of_index_only_scan(scan_i)) + + queue_use_cost(rowid_len, n) + + cost_of_row_retrieval + See get_merge_buffers_cost function for queue_use_cost formula derivation. + */ + + double roru_total_cost; + roru_total_cost= roru_index_costs + + rows2double(roru_total_records)*log((double)n_child_scans) / + (TIME_FOR_COMPARE_ROWID * M_LN2) + + get_sweep_read_cost(param, roru_total_records); + + DBUG_PRINT("info", ("ROR-union: cost %g, %zu members", + roru_total_cost, n_child_scans)); + trace_best_disjunct.add("index_roworder_union_cost", roru_total_cost) + .add("members", n_child_scans); + TRP_ROR_UNION* roru; + if (roru_total_cost < read_time) + { + if ((roru= new (param->mem_root) TRP_ROR_UNION)) + { + trace_best_disjunct.add("chosen", true); + roru->first_ror= roru_read_plans; + roru->last_ror= roru_read_plans + n_child_scans; + roru->read_cost= roru_total_cost; + roru->records= roru_total_records; + DBUG_RETURN(roru); + } + } + else + trace_best_disjunct.add("chosen", false); + DBUG_RETURN(imerge_trp); +} + + +/* + Merge index scans for the same indexes in an index merge plan + + SYNOPSIS + merge_same_index_scans() + param Context info for the operation + imerge IN/OUT SEL_IMERGE from which imerge_trp has been extracted + imerge_trp The index merge plan where index scans for the same + indexes are to be merges + read_time The upper bound for the cost of the plan to be evaluated + + DESRIPTION + For the given index merge plan imerge_trp extracted from the SEL_MERGE + imerge the function looks for range scans with the same indexes and merges + them into SEL_ARG trees. Then for each such SEL_ARG tree r_i the function + creates a range tree rt_i that contains only r_i. All rt_i are joined + into one index merge that replaces the original index merge imerge. + The function calls get_best_disjunct_quick for the new index merge to + get a new index merge plan that contains index scans only for different + indexes. + If there are no index scans for the same index in the original index + merge plan the function does not change the original imerge and returns + imerge_trp as its result. + + RETURN + The original or or improved index merge plan +*/ + +static +TABLE_READ_PLAN *merge_same_index_scans(PARAM *param, SEL_IMERGE *imerge, + TRP_INDEX_MERGE *imerge_trp, + double read_time) +{ + uint16 first_scan_tree_idx[MAX_KEY]; + SEL_TREE **tree; + TRP_RANGE **cur_child; + uint removed_cnt= 0; + + DBUG_ENTER("merge_same_index_scans"); + + bzero(first_scan_tree_idx, sizeof(first_scan_tree_idx[0])*param->keys); + + for (tree= imerge->trees, cur_child= imerge_trp->range_scans; + tree != imerge->trees_next; + tree++, cur_child++) + { + DBUG_ASSERT(tree); + uint key_idx= (*cur_child)->key_idx; + uint16 *tree_idx_ptr= &first_scan_tree_idx[key_idx]; + if (!*tree_idx_ptr) + *tree_idx_ptr= (uint16) (tree-imerge->trees+1); + else + { + SEL_TREE **changed_tree= imerge->trees+(*tree_idx_ptr-1); + SEL_ARG *key= (*changed_tree)->keys[key_idx]; + for (uint i= 0; i < param->keys; i++) + (*changed_tree)->keys[i]= NULL; + (*changed_tree)->keys_map.clear_all(); + if (key) + key->incr_refs(); + if ((*tree)->keys[key_idx]) + (*tree)->keys[key_idx]->incr_refs(); + if (((*changed_tree)->keys[key_idx]= + key_or_with_limit(param, key_idx, key, (*tree)->keys[key_idx]))) + (*changed_tree)->keys_map.set_bit(key_idx); + *tree= NULL; + removed_cnt++; + } + } + if (!removed_cnt) + DBUG_RETURN(imerge_trp); + + TABLE_READ_PLAN *trp= NULL; + SEL_TREE **new_trees_next= imerge->trees; + for (tree= new_trees_next; tree != imerge->trees_next; tree++) + { + if (!*tree) + continue; + if (tree > new_trees_next) + *new_trees_next= *tree; + new_trees_next++; + } + imerge->trees_next= new_trees_next; + + DBUG_ASSERT(imerge->trees_next>imerge->trees); + + if (imerge->trees_next-imerge->trees > 1) + trp= get_best_disjunct_quick(param, imerge, read_time); + else + { + /* + This alternative theoretically can be reached when the cost + of the index merge for such a formula as + (key1 BETWEEN c1_1 AND c1_2) AND key2 > c2 OR + (key1 BETWEEN c1_3 AND c1_4) AND key3 > c3 + is estimated as being cheaper than the cost of index scan for + the formula + (key1 BETWEEN c1_1 AND c1_2) OR (key1 BETWEEN c1_3 AND c1_4) + + In the current code this may happen for two reasons: + 1. for a single index range scan data records are accessed in + a random order + 2. the functions that estimate the cost of a range scan and an + index merge retrievals are not well calibrated + + As the best range access has been already chosen it does not + make sense to evaluate the one obtained from a degenerated + index merge. + */ + trp= 0; + } + + DBUG_RETURN(trp); +} + + +/* + This structure contains the info common for all steps of a partial + index intersection plan. Morever it contains also the info common + for index intersect plans. This info is filled in by the function + prepare_search_best just before searching for the best index + intersection plan. +*/ + +typedef struct st_common_index_intersect_info +{ + PARAM *param; /* context info for range optimizations */ + uint key_size; /* size of a ROWID element stored in Unique object */ + double compare_factor; /* 1/compare - cost to compare two ROWIDs */ + size_t max_memory_size; /* maximum space allowed for Unique objects */ + ha_rows table_cardinality; /* estimate of the number of records in table */ + double cutoff_cost; /* discard index intersects with greater costs */ + INDEX_SCAN_INFO *cpk_scan; /* clustered primary key used in intersection */ + + bool in_memory; /* unique object for intersection is completely in memory */ + + INDEX_SCAN_INFO **search_scans; /* scans possibly included in intersect */ + uint n_search_scans; /* number of elements in search_scans */ + + bool best_uses_cpk; /* current best intersect uses clustered primary key */ + double best_cost; /* cost of the current best index intersection */ + /* estimate of the number of records in the current best intersection */ + ha_rows best_records; + uint best_length; /* number of indexes in the current best intersection */ + INDEX_SCAN_INFO **best_intersect; /* the current best index intersection */ + /* scans from the best intersect to be filtrered by cpk conditions */ + key_map filtered_scans; + + uint *buff_elems; /* buffer to calculate cost of index intersection */ + +} COMMON_INDEX_INTERSECT_INFO; + + +/* + This structure contains the info specific for one step of an index + intersection plan. The structure is filled in by the function + check_index_intersect_extension. +*/ + +typedef struct st_partial_index_intersect_info +{ + COMMON_INDEX_INTERSECT_INFO *common_info; /* shared by index intersects */ + uint length; /* number of index scans in the partial intersection */ + ha_rows records; /* estimate of the number of records in intersection */ + double cost; /* cost of the partial index intersection */ + + /* estimate of total number of records of all scans of the partial index + intersect sent to the Unique object used for the intersection */ + ha_rows records_sent_to_unique; + + /* total cost of the scans of indexes from the partial index intersection */ + double index_read_cost; + + bool use_cpk_filter; /* cpk filter is to be used for this scan */ + bool in_memory; /* uses unique object in memory */ + double in_memory_cost; /* cost of using unique object in memory */ + + key_map filtered_scans; /* scans to be filtered by cpk conditions */ + + MY_BITMAP *intersect_fields; /* bitmap of fields used in intersection */ + + void init() + { + common_info= NULL; + intersect_fields= NULL; + records_sent_to_unique= records= length= in_memory= use_cpk_filter= 0; + cost= index_read_cost= in_memory_cost= 0.0; + filtered_scans.clear_all(); + } +} PARTIAL_INDEX_INTERSECT_INFO; + + +/* Check whether two indexes have the same first n components */ + +static +bool same_index_prefix(KEY *key1, KEY *key2, uint used_parts) +{ + KEY_PART_INFO *part1= key1->key_part; + KEY_PART_INFO *part2= key2->key_part; + for(uint i= 0; i < used_parts; i++, part1++, part2++) + { + if (part1->fieldnr != part2->fieldnr) + return FALSE; + } + return TRUE; +} + + +/* Create a bitmap for all fields of a table */ + +static +bool create_fields_bitmap(PARAM *param, MY_BITMAP *fields_bitmap) +{ + my_bitmap_map *bitmap_buf; + + if (!(bitmap_buf= (my_bitmap_map *) alloc_root(param->mem_root, + param->fields_bitmap_size))) + return TRUE; + if (my_bitmap_init(fields_bitmap, bitmap_buf, param->table->s->fields, FALSE)) + return TRUE; + + return FALSE; +} + +/* Compare two indexes scans for sort before search for the best intersection */ + +static +int cmp_intersect_index_scan(INDEX_SCAN_INFO **a, INDEX_SCAN_INFO **b) +{ + return (*a)->records < (*b)->records ? + -1 : (*a)->records == (*b)->records ? 0 : 1; +} + + +static inline +void set_field_bitmap_for_index_prefix(MY_BITMAP *field_bitmap, + KEY_PART_INFO *key_part, + uint used_key_parts) +{ + bitmap_clear_all(field_bitmap); + for (KEY_PART_INFO *key_part_end= key_part+used_key_parts; + key_part < key_part_end; key_part++) + { + bitmap_set_bit(field_bitmap, key_part->fieldnr-1); + } +} + + +/* + Round up table cardinality read from statistics provided by engine. + This function should go away when mysql test will allow to handle + more or less easily in the test suites deviations of InnoDB + statistical data. +*/ + +static inline +ha_rows get_table_cardinality_for_index_intersect(TABLE *table) +{ + if (table->file->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT) + return table->stat_records(); + else + { + ha_rows d; + double q; + for (q= (double)table->stat_records(), d= 1 ; q >= 10; q/= 10, d*= 10 ) ; + return (ha_rows) (floor(q+0.5) * d); + } +} + +static +void print_keyparts(THD *thd, KEY *key, uint key_parts) +{ + DBUG_ASSERT(thd->trace_started()); + + KEY_PART_INFO *part= key->key_part; + Json_writer_array keyparts= Json_writer_array(thd, "keyparts"); + for(uint i= 0; i < key_parts; i++, part++) + keyparts.add(part->field->field_name); +} + + +static +ha_rows records_in_index_intersect_extension(PARTIAL_INDEX_INTERSECT_INFO *curr, + INDEX_SCAN_INFO *ext_index_scan); + +/* + Prepare to search for the best index intersection + + SYNOPSIS + prepare_search_best_index_intersect() + param common info about index ranges + tree tree of ranges for indexes than can be intersected + common OUT info needed for search to be filled by the function + init OUT info for an initial pseudo step of the intersection plans + cutoff_cost cut off cost of the interesting index intersection + + DESCRIPTION + The function initializes all fields of the structure 'common' to be used + when searching for the best intersection plan. It also allocates + memory to store the most cheap index intersection. + + NOTES + When selecting candidates for index intersection we always take only + one representative out of any set of indexes that share the same range + conditions. These indexes always have the same prefixes and the + components of this prefixes are exactly those used in these range + conditions. + Range conditions over clustered primary key (cpk) is always used only + as the condition that filters out some rowids retrieved by the scans + for secondary indexes. The cpk index will be handled in special way by + the function that search for the best index intersection. + + RETURN + FALSE in the case of success + TRUE otherwise +*/ + +static +bool prepare_search_best_index_intersect(PARAM *param, + SEL_TREE *tree, + COMMON_INDEX_INTERSECT_INFO *common, + PARTIAL_INDEX_INTERSECT_INFO *init, + double cutoff_cost) +{ + uint i; + uint n_search_scans; + double cost; + INDEX_SCAN_INFO **index_scan; + INDEX_SCAN_INFO **scan_ptr; + INDEX_SCAN_INFO *cpk_scan= NULL; + TABLE *table= param->table; + uint n_index_scans= (uint)(tree->index_scans_end - tree->index_scans); + THD *thd= param->thd; + + if (n_index_scans <= 1) + return 1; + + init->init(); + init->common_info= common; + init->cost= cutoff_cost; + + common->param= param; + common->key_size= table->file->ref_length; + common->compare_factor= TIME_FOR_COMPARE_ROWID; + common->max_memory_size= (size_t)param->thd->variables.sortbuff_size; + common->cutoff_cost= cutoff_cost; + common->cpk_scan= NULL; + common->table_cardinality= + get_table_cardinality_for_index_intersect(table); + + if (table->file->ha_table_flags() & HA_TABLE_SCAN_ON_INDEX) + { + INDEX_SCAN_INFO **index_scan_end; + index_scan= tree->index_scans; + index_scan_end= index_scan+n_index_scans; + for ( ; index_scan < index_scan_end; index_scan++) + { + if (table->file->is_clustering_key((*index_scan)->keynr)) + { + common->cpk_scan= cpk_scan= *index_scan; + break; + } + } + } + + i= n_index_scans - MY_TEST(cpk_scan != NULL) + 1; + + if (!(common->search_scans = + (INDEX_SCAN_INFO **) alloc_root (param->mem_root, + sizeof(INDEX_SCAN_INFO *) * i))) + return TRUE; + bzero(common->search_scans, sizeof(INDEX_SCAN_INFO *) * i); + + INDEX_SCAN_INFO **selected_index_scans= common->search_scans; + Json_writer_array potential_idx_scans(thd, "potential_index_scans"); + for (i=0, index_scan= tree->index_scans; i < n_index_scans; i++, index_scan++) + { + Json_writer_object idx_scan(thd); + uint used_key_parts= (*index_scan)->used_key_parts; + KEY *key_info= (*index_scan)->key_info; + idx_scan.add("index", key_info->name); + + if (*index_scan == cpk_scan) + { + idx_scan.add("chosen", "false") + .add("cause", "clustered index used for filtering"); + continue; + } + if (cpk_scan && cpk_scan->used_key_parts >= used_key_parts && + same_index_prefix(cpk_scan->key_info, key_info, used_key_parts)) + { + idx_scan.add("chosen", "false") + .add("cause", "clustered index used for filtering"); + continue; + } + + cost= table->opt_range[(*index_scan)->keynr].index_only_cost; + + idx_scan.add("cost", cost); + + if (cost >= cutoff_cost) + { + idx_scan.add("chosen", false); + idx_scan.add("cause", "cost"); + continue; + } + + for (scan_ptr= selected_index_scans; *scan_ptr ; scan_ptr++) + { + /* + When we have range conditions for two different indexes with the same + beginning it does not make sense to consider both of them for index + intersection if the range conditions are covered by common initial + components of the indexes. Actually in this case the indexes are + guaranteed to have the same range conditions. + */ + if ((*scan_ptr)->used_key_parts == used_key_parts && + same_index_prefix((*scan_ptr)->key_info, key_info, used_key_parts)) + break; + } + if (!*scan_ptr || cost < (*scan_ptr)->index_read_cost) + { + idx_scan.add("chosen", true); + if (!*scan_ptr) + idx_scan.add("cause", "first occurrence of index prefix"); + else + idx_scan.add("cause", "better cost for same idx prefix"); + *scan_ptr= *index_scan; + (*scan_ptr)->index_read_cost= cost; + } + else + { + idx_scan.add("chosen", false).add("cause", "cost"); + } + } + potential_idx_scans.end(); + + ha_rows records_in_scans= 0; + + for (scan_ptr=selected_index_scans, i= 0; *scan_ptr; scan_ptr++, i++) + { + if (create_fields_bitmap(param, &(*scan_ptr)->used_fields)) + return TRUE; + records_in_scans+= (*scan_ptr)->records; + } + + n_search_scans= i; + + if (cpk_scan && create_fields_bitmap(param, &cpk_scan->used_fields)) + return TRUE; + + if (!(common->n_search_scans= n_search_scans)) + return TRUE; + + common->best_uses_cpk= FALSE; + common->best_cost= cutoff_cost + COST_EPS; + common->best_length= 0; + + if (!(common->best_intersect= + (INDEX_SCAN_INFO **) alloc_root (param->mem_root, + sizeof(INDEX_SCAN_INFO *) * + (i + MY_TEST(cpk_scan != NULL))))) + return TRUE; + + size_t calc_cost_buff_size= + Unique::get_cost_calc_buff_size((size_t)records_in_scans, + common->key_size, + common->max_memory_size); + if (!(common->buff_elems= (uint *) alloc_root(param->mem_root, + calc_cost_buff_size))) + return TRUE; + + my_qsort(selected_index_scans, n_search_scans, sizeof(INDEX_SCAN_INFO *), + (qsort_cmp) cmp_intersect_index_scan); + + Json_writer_array selected_idx_scans(thd, "selected_index_scans"); + if (cpk_scan) + { + PARTIAL_INDEX_INTERSECT_INFO curr; + set_field_bitmap_for_index_prefix(&cpk_scan->used_fields, + cpk_scan->key_info->key_part, + cpk_scan->used_key_parts); + curr.common_info= common; + curr.intersect_fields= &cpk_scan->used_fields; + curr.records= cpk_scan->records; + curr.length= 1; + for (scan_ptr=selected_index_scans; *scan_ptr; scan_ptr++) + { + KEY *key_info= (*scan_ptr)->key_info; + ha_rows scan_records= (*scan_ptr)->records; + ha_rows records= records_in_index_intersect_extension(&curr, *scan_ptr); + (*scan_ptr)->filtered_out= records >= scan_records ? + 0 : scan_records-records; + if (thd->trace_started()) + { + Json_writer_object selected_idx(thd); + selected_idx.add("index", key_info->name); + print_keyparts(thd, key_info, (*scan_ptr)->used_key_parts); + selected_idx.add("records", (*scan_ptr)->records) + .add("filtered_records", (*scan_ptr)->filtered_out); + } + } + } + else + { + for (scan_ptr=selected_index_scans; *scan_ptr; scan_ptr++) + { + KEY *key_info= (*scan_ptr)->key_info; + (*scan_ptr)->filtered_out= 0; + if (thd->trace_started()) + { + Json_writer_object selected_idx(thd); + selected_idx.add("index", key_info->name); + print_keyparts(thd, key_info, (*scan_ptr)->used_key_parts); + selected_idx.add("records", (*scan_ptr)->records) + .add("filtered_records", (*scan_ptr)->filtered_out); + } + } + } + + return FALSE; +} + + +/* + On Estimation of the Number of Records in an Index Intersection + =============================================================== + + Consider query Q over table t. Let C be the WHERE condition of this query, + and, idx1(a1_1,...,a1_k1) and idx2(a2_1,...,a2_k2) be some indexes defined + on table t. + Let rt1 and rt2 be the range trees extracted by the range optimizer from C + for idx1 and idx2 respectively. + Let #t be the estimate of the number of records in table t provided for the + optimizer. + Let #r1 and #r2 be the estimates of the number of records in the range trees + rt1 and rt2, respectively, obtained by the range optimizer. + + We need to get an estimate for the number of records in the index + intersection of rt1 and rt2. In other words, we need to estimate the + cardinality of the set of records that are in both trees. Let's designate + this number by #r. + + If we do not make any assumptions then we can only state that + #r<=MY_MIN(#r1,#r2). + With this estimate we can't say that the index intersection scan will be + cheaper than the cheapest index scan. + + Let Rt1 and Rt2 be AND/OR conditions representing rt and rt2 respectively. + The probability that a record belongs to rt1 is sel(Rt1)=#r1/#t. + The probability that a record belongs to rt2 is sel(Rt2)=#r2/#t. + + If we assume that the values in columns of idx1 and idx2 are independent + then #r/#t=sel(Rt1&Rt2)=sel(Rt1)*sel(Rt2)=(#r1/#t)*(#r2/#t). + So in this case we have: #r=#r1*#r2/#t. + + The above assumption of independence of the columns in idx1 and idx2 means + that: + - all columns are different + - values from one column do not correlate with values from any other column. + + We can't help with the case when column correlate with each other. + Yet, if they are assumed to be uncorrelated the value of #r theoretically can + be evaluated . Unfortunately this evaluation, in general, is rather complex. + + Let's consider two indexes idx1:(dept, manager), idx2:(dept, building) + over table 'employee' and two range conditions over these indexes: + Rt1: dept=10 AND manager LIKE 'S%' + Rt2: dept=10 AND building LIKE 'L%'. + We can state that: + sel(Rt1&Rt2)=sel(dept=10)*sel(manager LIKE 'S%')*sel(building LIKE 'L%') + =sel(Rt1)*sel(Rt2)/sel(dept=10). + sel(Rt1/2_0:dept=10) can be estimated if we know the cardinality #r1_0 of + the range for sub-index idx1_0 (dept) of the index idx1 or the cardinality + #rt2_0 of the same range for sub-index idx2_0(dept) of the index idx2. + The current code does not make an estimate either for #rt1_0, or for #rt2_0, + but it can be adjusted to provide those numbers. + Alternatively, MY_MIN(rec_per_key) for (dept) could be used to get an upper + bound for the value of sel(Rt1&Rt2). Yet this statistics is not provided + now. + + Let's consider two other indexes idx1:(dept, last_name), + idx2:(first_name, last_name) and two range conditions over these indexes: + Rt1: dept=5 AND last_name='Sm%' + Rt2: first_name='Robert' AND last_name='Sm%'. + + sel(Rt1&Rt2)=sel(dept=5)*sel(last_name='Sm5')*sel(first_name='Robert') + =sel(Rt2)*sel(dept=5) + Here MY_MAX(rec_per_key) for (dept) could be used to get an upper bound for + the value of sel(Rt1&Rt2). + + When the intersected indexes have different major columns, but some + minor column are common the picture may be more complicated. + + Let's consider the following range conditions for the same indexes as in + the previous example: + Rt1: (Rt11: dept=5 AND last_name='So%') + OR + (Rt12: dept=7 AND last_name='Saw%') + Rt2: (Rt21: first_name='Robert' AND last_name='Saw%') + OR + (Rt22: first_name='Bob' AND last_name='So%') + Here we have: + sel(Rt1&Rt2)= sel(Rt11)*sel(Rt21)+sel(Rt22)*sel(dept=5) + + sel(Rt21)*sel(dept=7)+sel(Rt12)*sel(Rt22) + Now consider the range condition: + Rt1_0: (dept=5 OR dept=7) + For this condition we can state that: + sel(Rt1_0&Rt2)=(sel(dept=5)+sel(dept=7))*(sel(Rt21)+sel(Rt22))= + sel(dept=5)*sel(Rt21)+sel(dept=7)*sel(Rt21)+ + sel(dept=5)*sel(Rt22)+sel(dept=7)*sel(Rt22)= + sel(dept=5)*sel(Rt21)+sel(Rt21)*sel(dept=7)+ + sel(Rt22)*sel(dept=5)+sel(dept=7)*sel(Rt22) > + sel(Rt11)*sel(Rt21)+sel(Rt22)*sel(dept=5)+ + sel(Rt21)*sel(dept=7)+sel(Rt12)*sel(Rt22) > + sel(Rt1 & Rt2) + + We've just demonstrated for an example what is intuitively almost obvious + in general. We can remove the ending parts fromrange trees getting less + selective range conditions for sub-indexes. + So if not a most major component with the number k of an index idx is + encountered in the index with which we intersect we can use the sub-index + idx_k-1 that includes the components of idx up to the i-th component and + the range tree for idx_k-1 to make an upper bound estimate for the number + of records in the index intersection. + The range tree for idx_k-1 we use here is the subtree of the original range + tree for idx that contains only parts from the first k-1 components. + + As it was mentioned above the range optimizer currently does not provide + an estimate for the number of records in the ranges for sub-indexes. + However, some reasonable upper bound estimate can be obtained. + + Let's consider the following range tree: + Rt: (first_name='Robert' AND last_name='Saw%') + OR + (first_name='Bob' AND last_name='So%') + Let #r be the number of records in Rt. Let f_1 be the fan-out of column + last_name: + f_1 = rec_per_key[first_name]/rec_per_key[last_name]. + The the number of records in the range tree: + Rt_0: (first_name='Robert' OR first_name='Bob') + for the sub-index (first_name) is not greater than MY_MAX(#r*f_1, #t). + Strictly speaking, we can state only that it's not greater than + MY_MAX(#r*max_f_1, #t), where + max_f_1= max_rec_per_key[first_name]/min_rec_per_key[last_name]. + Yet, if #r/#t is big enough (and this is the case of an index intersection, + because using this index range with a single index scan is cheaper than + the cost of the intersection when #r/#t is small) then almost safely we + can use here f_1 instead of max_f_1. + + The above considerations can be used in future development. Now, they are + used partly in the function that provides a rough upper bound estimate for + the number of records in an index intersection that follow below. +*/ + +/* + Estimate the number of records selected by an extension a partial intersection + + SYNOPSIS + records_in_index_intersect_extension() + curr partial intersection plan to be extended + ext_index_scan the evaluated extension of this partial plan + + DESCRIPTION + The function provides an estimate for the number of records in the + intersection of the partial index intersection curr with the index + ext_index_scan. If all intersected indexes does not have common columns + then the function returns an exact estimate (assuming there are no + correlations between values in the columns). If the intersected indexes + have common columns the function returns an upper bound for the number + of records in the intersection provided that the intersection of curr + with ext_index_scan can is expected to have less records than the expected + number of records in the partial intersection curr. In this case the + function also assigns the bitmap of the columns in the extended + intersection to ext_index_scan->used_fields. + If the function cannot expect that the number of records in the extended + intersection is less that the expected number of records #r in curr then + the function returns a number bigger than #r. + + NOTES + See the comment before the desription of the function that explains the + reasoning used by this function. + + RETURN + The expected number of rows in the extended index intersection +*/ + +static +ha_rows records_in_index_intersect_extension(PARTIAL_INDEX_INTERSECT_INFO *curr, + INDEX_SCAN_INFO *ext_index_scan) +{ + KEY *key_info= ext_index_scan->key_info; + KEY_PART_INFO* key_part= key_info->key_part; + uint used_key_parts= ext_index_scan->used_key_parts; + MY_BITMAP *used_fields= &ext_index_scan->used_fields; + + if (!curr->length) + { + /* + If this the first index in the intersection just mark the + fields in the used_fields bitmap and return the expected + number of records in the range scan for the index provided + by the range optimizer. + */ + set_field_bitmap_for_index_prefix(used_fields, key_part, used_key_parts); + return ext_index_scan->records; + } + + uint i; + bool better_selectivity= FALSE; + ha_rows records= curr->records; + MY_BITMAP *curr_intersect_fields= curr->intersect_fields; + for (i= 0; i < used_key_parts; i++, key_part++) + { + if (bitmap_is_set(curr_intersect_fields, key_part->fieldnr-1)) + break; + } + if (i) + { + ha_rows table_cardinality= curr->common_info->table_cardinality; + ha_rows ext_records= ext_index_scan->records; + if (i < used_key_parts) + { + double f1= key_info->actual_rec_per_key(i-1); + double f2= key_info->actual_rec_per_key(i); + ext_records= (ha_rows) ((double) ext_records / f2 * f1); + } + if (ext_records < table_cardinality) + { + better_selectivity= TRUE; + records= (ha_rows) ((double) records / table_cardinality * + ext_records); + bitmap_copy(used_fields, curr_intersect_fields); + key_part= key_info->key_part; + for (uint j= 0; j < used_key_parts; j++, key_part++) + bitmap_set_bit(used_fields, key_part->fieldnr-1); + } + } + return !better_selectivity ? records+1 : + !records ? 1 : records; +} + + +/* + Estimate the cost a binary search within disjoint cpk range intervals + + Number of comparisons to check whether a cpk value satisfies + the cpk range condition = log2(cpk_scan->range_count). +*/ + +static inline +double get_cpk_filter_cost(ha_rows filtered_records, + INDEX_SCAN_INFO *cpk_scan, + double compare_factor) +{ + return log((double) (cpk_scan->range_count+1)) / (compare_factor * M_LN2) * + filtered_records; +} + + +/* + Check whether a patial index intersection plan can be extended + + SYNOPSIS + check_index_intersect_extension() + curr partial intersection plan to be extended + ext_index_scan a possible extension of this plan to be checked + next OUT the structure to be filled for the extended plan + + DESCRIPTION + The function checks whether it makes sense to extend the index + intersection plan adding the index ext_index_scan, and, if this + the case, the function fills in the structure for the extended plan. + + RETURN + TRUE if it makes sense to extend the given plan + FALSE otherwise +*/ + +static +bool check_index_intersect_extension(PARTIAL_INDEX_INTERSECT_INFO *curr, + INDEX_SCAN_INFO *ext_index_scan, + PARTIAL_INDEX_INTERSECT_INFO *next) +{ + ha_rows records; + ha_rows records_sent_to_unique; + double cost; + ha_rows ext_index_scan_records= ext_index_scan->records; + ha_rows records_filtered_out_by_cpk= ext_index_scan->filtered_out; + COMMON_INDEX_INTERSECT_INFO *common_info= curr->common_info; + double cutoff_cost= common_info->cutoff_cost; + uint idx= curr->length; + next->index_read_cost= curr->index_read_cost+ext_index_scan->index_read_cost; + if (next->index_read_cost > cutoff_cost) + return FALSE; + + if ((next->in_memory= curr->in_memory)) + next->in_memory_cost= curr->in_memory_cost; + + next->intersect_fields= &ext_index_scan->used_fields; + next->filtered_scans= curr->filtered_scans; + + records_sent_to_unique= curr->records_sent_to_unique; + + next->use_cpk_filter= FALSE; + + /* Calculate the cost of using a Unique object for index intersection */ + if (idx && next->in_memory) + { + /* + All rowids received from the first scan are expected in one unique tree + */ + ha_rows elems_in_tree= common_info->search_scans[0]->records- + common_info->search_scans[0]->filtered_out ; + next->in_memory_cost+= Unique::get_search_cost(elems_in_tree, + common_info->compare_factor)* + ext_index_scan_records; + cost= next->in_memory_cost; + } + else + { + uint *buff_elems= common_info->buff_elems; + uint key_size= common_info->key_size; + double compare_factor= common_info->compare_factor; + size_t max_memory_size= common_info->max_memory_size; + + records_sent_to_unique+= ext_index_scan_records; + cost= Unique::get_use_cost(buff_elems, (size_t) records_sent_to_unique, key_size, + max_memory_size, compare_factor, TRUE, + &next->in_memory); + if (records_filtered_out_by_cpk) + { + /* Check whether using cpk filter for this scan is beneficial */ + + double cost2; + bool in_memory2; + ha_rows records2= records_sent_to_unique-records_filtered_out_by_cpk; + cost2= Unique::get_use_cost(buff_elems, (size_t) records2, key_size, + max_memory_size, compare_factor, TRUE, + &in_memory2); + cost2+= get_cpk_filter_cost(ext_index_scan_records, common_info->cpk_scan, + compare_factor); + if (cost > cost2 + COST_EPS) + { + cost= cost2; + next->in_memory= in_memory2; + next->use_cpk_filter= TRUE; + records_sent_to_unique= records2; + } + + } + if (next->in_memory) + next->in_memory_cost= cost; + } + + if (next->use_cpk_filter) + { + next->filtered_scans.set_bit(ext_index_scan->keynr); + bitmap_union(&ext_index_scan->used_fields, + &common_info->cpk_scan->used_fields); + } + next->records_sent_to_unique= records_sent_to_unique; + + records= records_in_index_intersect_extension(curr, ext_index_scan); + if (idx && records > curr->records) + return FALSE; + if (next->use_cpk_filter && curr->filtered_scans.is_clear_all()) + records-= records_filtered_out_by_cpk; + next->records= records; + + cost+= next->index_read_cost; + if (cost >= cutoff_cost) + return FALSE; + + cost+= get_sweep_read_cost(common_info->param, records); + + next->cost= cost; + next->length= curr->length+1; + + return TRUE; +} + + +/* + Search for the cheapest extensions of range scans used to access a table + + SYNOPSIS + find_index_intersect_best_extension() + curr partial intersection to evaluate all possible extension for + + DESCRIPTION + The function tries to extend the partial plan curr in all possible ways + to look for a cheapest index intersection whose cost less than the + cut off value set in curr->common_info.cutoff_cost. +*/ + +static +void find_index_intersect_best_extension(PARTIAL_INDEX_INTERSECT_INFO *curr) +{ + PARTIAL_INDEX_INTERSECT_INFO next; + COMMON_INDEX_INTERSECT_INFO *common_info= curr->common_info; + INDEX_SCAN_INFO **index_scans= common_info->search_scans; + uint idx= curr->length; + INDEX_SCAN_INFO **rem_first_index_scan_ptr= &index_scans[idx]; + double cost= curr->cost; + + if (cost + COST_EPS < common_info->best_cost) + { + common_info->best_cost= cost; + common_info->best_length= curr->length; + common_info->best_records= curr->records; + common_info->filtered_scans= curr->filtered_scans; + /* common_info->best_uses_cpk <=> at least one scan uses a cpk filter */ + common_info->best_uses_cpk= !curr->filtered_scans.is_clear_all(); + uint sz= sizeof(INDEX_SCAN_INFO *) * curr->length; + memcpy(common_info->best_intersect, common_info->search_scans, sz); + common_info->cutoff_cost= cost; + } + + if (!(*rem_first_index_scan_ptr)) + return; + + next.common_info= common_info; + + INDEX_SCAN_INFO *rem_first_index_scan= *rem_first_index_scan_ptr; + for (INDEX_SCAN_INFO **index_scan_ptr= rem_first_index_scan_ptr; + *index_scan_ptr; index_scan_ptr++) + { + *rem_first_index_scan_ptr= *index_scan_ptr; + *index_scan_ptr= rem_first_index_scan; + if (check_index_intersect_extension(curr, *rem_first_index_scan_ptr, &next)) + find_index_intersect_best_extension(&next); + *index_scan_ptr= *rem_first_index_scan_ptr; + *rem_first_index_scan_ptr= rem_first_index_scan; + } +} + + +/* + Get the plan of the best intersection of range scans used to access a table + + SYNOPSIS + get_best_index_intersect() + param common info about index ranges + tree tree of ranges for indexes than can be intersected + read_time cut off value for the evaluated plans + + DESCRIPTION + The function looks for the cheapest index intersection of the range + scans to access a table. The info about the ranges for all indexes + is provided by the range optimizer and is passed through the + parameters param and tree. Any plan whose cost is greater than read_time + is rejected. + After the best index intersection is found the function constructs + the structure that manages the execution by the chosen plan. + + RETURN + Pointer to the generated execution structure if a success, + 0 - otherwise. +*/ + +static +TRP_INDEX_INTERSECT *get_best_index_intersect(PARAM *param, SEL_TREE *tree, + double read_time) +{ + uint i; + uint count; + TRP_RANGE **cur_range; + TRP_RANGE **range_scans; + INDEX_SCAN_INFO *index_scan; + COMMON_INDEX_INTERSECT_INFO common; + PARTIAL_INDEX_INTERSECT_INFO init; + TRP_INDEX_INTERSECT *intersect_trp= NULL; + TABLE *table= param->table; + THD *thd= param->thd; + + DBUG_ENTER("get_best_index_intersect"); + + Json_writer_object trace_idx_interect(thd, "analyzing_sort_intersect"); + + if (prepare_search_best_index_intersect(param, tree, &common, &init, + read_time)) + DBUG_RETURN(NULL); + + find_index_intersect_best_extension(&init); + + if (common.best_length <= 1 && !common.best_uses_cpk) + DBUG_RETURN(NULL); + + if (common.best_uses_cpk) + { + memmove((char *) (common.best_intersect+1), (char *) common.best_intersect, + sizeof(INDEX_SCAN_INFO *) * common.best_length); + common.best_intersect[0]= common.cpk_scan; + common.best_length++; + } + + count= common.best_length; + + if (!(range_scans= (TRP_RANGE**)alloc_root(param->mem_root, + sizeof(TRP_RANGE *)* + count))) + DBUG_RETURN(NULL); + + for (i= 0, cur_range= range_scans; i < count; i++) + { + index_scan= common.best_intersect[i]; + if ((*cur_range= new (param->mem_root) TRP_RANGE(index_scan->sel_arg, + index_scan->idx, 0))) + { + TRP_RANGE *trp= *cur_range; + trp->read_cost= index_scan->index_read_cost; + trp->records= index_scan->records; + trp->is_ror= FALSE; + trp->mrr_buf_size= 0; + table->intersect_keys.set_bit(index_scan->keynr); + cur_range++; + } + } + + count= (uint)(tree->index_scans_end - tree->index_scans); + for (i= 0; i < count; i++) + { + index_scan= tree->index_scans[i]; + if (!table->intersect_keys.is_set(index_scan->keynr)) + { + for (uint j= 0; j < common.best_length; j++) + { + INDEX_SCAN_INFO *scan= common.best_intersect[j]; + if (same_index_prefix(index_scan->key_info, scan->key_info, + scan->used_key_parts)) + { + table->intersect_keys.set_bit(index_scan->keynr); + break; + } + } + } + } + + if ((intersect_trp= new (param->mem_root)TRP_INDEX_INTERSECT)) + { + + intersect_trp->read_cost= common.best_cost; + intersect_trp->records= common.best_records; + intersect_trp->range_scans= range_scans; + intersect_trp->range_scans_end= cur_range; + intersect_trp->filtered_scans= common.filtered_scans; + trace_idx_interect.add("rows", intersect_trp->records) + .add("cost", intersect_trp->read_cost) + .add("chosen",true); + } + DBUG_RETURN(intersect_trp); +} + + +typedef struct st_ror_scan_info : INDEX_SCAN_INFO +{ +} ROR_SCAN_INFO; + +void TRP_ROR_INTERSECT::trace_basic_info(PARAM *param, + Json_writer_object *trace_object) const +{ + THD *thd= param->thd; + DBUG_ASSERT(trace_object->trace_started()); + + trace_object->add("type", "index_roworder_intersect"); + trace_object->add("rows", records); + trace_object->add("cost", read_cost); + trace_object->add("covering", is_covering); + trace_object->add("clustered_pk_scan", cpk_scan != NULL); + + Json_writer_array smth_trace(thd, "intersect_of"); + for (ROR_SCAN_INFO **cur_scan= first_scan; cur_scan != last_scan; + cur_scan++) + { + const KEY &cur_key= param->table->key_info[(*cur_scan)->keynr]; + const KEY_PART_INFO *key_part= cur_key.key_part; + + Json_writer_object trace_isect_idx(thd); + trace_isect_idx.add("type", "range_scan"); + trace_isect_idx.add("index", cur_key.name); + trace_isect_idx.add("rows", (*cur_scan)->records); + + Json_writer_array trace_range(thd, "ranges"); + + trace_ranges(&trace_range, param, (*cur_scan)->idx, + (*cur_scan)->sel_arg, key_part); + } +} + + +/* + Create ROR_SCAN_INFO* structure with a single ROR scan on index idx using + sel_arg set of intervals. + + SYNOPSIS + make_ror_scan() + param Parameter from test_quick_select function + idx Index of key in param->keys + sel_arg Set of intervals for a given key + + RETURN + NULL - out of memory + ROR scan structure containing a scan for {idx, sel_arg} +*/ + +static +ROR_SCAN_INFO *make_ror_scan(const PARAM *param, int idx, SEL_ARG *sel_arg) +{ + ROR_SCAN_INFO *ror_scan; + my_bitmap_map *bitmap_buf; + uint keynr; + DBUG_ENTER("make_ror_scan"); + + if (!(ror_scan= (ROR_SCAN_INFO*)alloc_root(param->mem_root, + sizeof(ROR_SCAN_INFO)))) + DBUG_RETURN(NULL); + + ror_scan->idx= idx; + ror_scan->keynr= keynr= param->real_keynr[idx]; + ror_scan->key_rec_length= (param->table->key_info[keynr].key_length + + param->table->file->ref_length); + ror_scan->sel_arg= sel_arg; + ror_scan->records= param->quick_rows[keynr]; + + if (!(bitmap_buf= (my_bitmap_map*) alloc_root(param->mem_root, + param->fields_bitmap_size))) + DBUG_RETURN(NULL); + + if (my_bitmap_init(&ror_scan->covered_fields, bitmap_buf, + param->table->s->fields, FALSE)) + DBUG_RETURN(NULL); + bitmap_clear_all(&ror_scan->covered_fields); + + KEY_PART_INFO *key_part= param->table->key_info[keynr].key_part; + KEY_PART_INFO *key_part_end= key_part + + param->table->key_info[keynr].user_defined_key_parts; + for (;key_part != key_part_end; ++key_part) + { + if (bitmap_is_set(¶m->needed_fields, key_part->fieldnr-1)) + bitmap_set_bit(&ror_scan->covered_fields, key_part->fieldnr-1); + } + ror_scan->index_read_cost= + param->table->file->keyread_time(ror_scan->keynr, 1, ror_scan->records); + DBUG_RETURN(ror_scan); +} + + +/* + Compare two ROR_SCAN_INFO** by E(#records_matched) * key_record_length. + SYNOPSIS + cmp_ror_scan_info() + a ptr to first compared value + b ptr to second compared value + + RETURN + -1 a < b + 0 a = b + 1 a > b +*/ + +static int cmp_ror_scan_info(ROR_SCAN_INFO** a, ROR_SCAN_INFO** b) +{ + double val1= rows2double((*a)->records) * (*a)->key_rec_length; + double val2= rows2double((*b)->records) * (*b)->key_rec_length; + return (val1 < val2)? -1: (val1 == val2)? 0 : 1; +} + +/* + Compare two ROR_SCAN_INFO** by + (#covered fields in F desc, + #components asc, + number of first not covered component asc) + + SYNOPSIS + cmp_ror_scan_info_covering() + a ptr to first compared value + b ptr to second compared value + + RETURN + -1 a < b + 0 a = b + 1 a > b +*/ + +static int cmp_ror_scan_info_covering(ROR_SCAN_INFO** a, ROR_SCAN_INFO** b) +{ + if ((*a)->used_fields_covered > (*b)->used_fields_covered) + return -1; + if ((*a)->used_fields_covered < (*b)->used_fields_covered) + return 1; + if ((*a)->key_components < (*b)->key_components) + return -1; + if ((*a)->key_components > (*b)->key_components) + return 1; + if ((*a)->first_uncovered_field < (*b)->first_uncovered_field) + return -1; + if ((*a)->first_uncovered_field > (*b)->first_uncovered_field) + return 1; + return 0; +} + + +/* Auxiliary structure for incremental ROR-intersection creation */ +typedef struct +{ + const PARAM *param; + MY_BITMAP covered_fields; /* union of fields covered by all scans */ + /* + Fraction of table records that satisfies conditions of all scans. + This is the number of full records that will be retrieved if a + non-index_only index intersection will be employed. + */ + double out_rows; + /* TRUE if covered_fields is a superset of needed_fields */ + bool is_covering; + + ha_rows index_records; /* sum(#records to look in indexes) */ + double index_scan_costs; /* SUM(cost of 'index-only' scans) */ + double total_cost; +} ROR_INTERSECT_INFO; + + +/* + Allocate a ROR_INTERSECT_INFO and initialize it to contain zero scans. + + SYNOPSIS + ror_intersect_init() + param Parameter from test_quick_select + + RETURN + allocated structure + NULL on error +*/ + +static +ROR_INTERSECT_INFO* ror_intersect_init(const PARAM *param) +{ + ROR_INTERSECT_INFO *info; + my_bitmap_map* buf; + if (!(info= (ROR_INTERSECT_INFO*)alloc_root(param->mem_root, + sizeof(ROR_INTERSECT_INFO)))) + return NULL; + info->param= param; + if (!(buf= (my_bitmap_map*) alloc_root(param->mem_root, + param->fields_bitmap_size))) + return NULL; + if (my_bitmap_init(&info->covered_fields, buf, param->table->s->fields, + FALSE)) + return NULL; + info->is_covering= FALSE; + info->index_scan_costs= 0.0; + info->index_records= 0; + info->out_rows= (double) param->table->stat_records(); + bitmap_clear_all(&info->covered_fields); + return info; +} + +void ror_intersect_cpy(ROR_INTERSECT_INFO *dst, const ROR_INTERSECT_INFO *src) +{ + dst->param= src->param; + memcpy(dst->covered_fields.bitmap, src->covered_fields.bitmap, + no_bytes_in_map(&src->covered_fields)); + dst->out_rows= src->out_rows; + dst->is_covering= src->is_covering; + dst->index_records= src->index_records; + dst->index_scan_costs= src->index_scan_costs; + dst->total_cost= src->total_cost; +} + + +/* + Get selectivity of a ROR scan wrt ROR-intersection. + + SYNOPSIS + ror_scan_selectivity() + info ROR-interection + scan ROR scan + + NOTES + Suppose we have a condition on several keys + cond=k_11=c_11 AND k_12=c_12 AND ... // parts of first key + k_21=c_21 AND k_22=c_22 AND ... // parts of second key + ... + k_n1=c_n1 AND k_n3=c_n3 AND ... (1) //parts of the key used by *scan + + where k_ij may be the same as any k_pq (i.e. keys may have common parts). + + A full row is retrieved if entire condition holds. + + The recursive procedure for finding P(cond) is as follows: + + First step: + Pick 1st part of 1st key and break conjunction (1) into two parts: + cond= (k_11=c_11 AND R) + + Here R may still contain condition(s) equivalent to k_11=c_11. + Nevertheless, the following holds: + + P(k_11=c_11 AND R) = P(k_11=c_11) * P(R | k_11=c_11). + + Mark k_11 as fixed field (and satisfied condition) F, save P(F), + save R to be cond and proceed to recursion step. + + Recursion step: + We have a set of fixed fields/satisfied conditions) F, probability P(F), + and remaining conjunction R + Pick next key part on current key and its condition "k_ij=c_ij". + We will add "k_ij=c_ij" into F and update P(F). + Lets denote k_ij as t, R = t AND R1, where R1 may still contain t. Then + + P((t AND R1)|F) = P(t|F) * P(R1|t|F) = P(t|F) * P(R1|(t AND F)) (2) + + (where '|' mean conditional probability, not "or") + + Consider the first multiplier in (2). One of the following holds: + a) F contains condition on field used in t (i.e. t AND F = F). + Then P(t|F) = 1 + + b) F doesn't contain condition on field used in t. Then F and t are + considered independent. + + P(t|F) = P(t|(fields_before_t_in_key AND other_fields)) = + = P(t|fields_before_t_in_key). + + P(t|fields_before_t_in_key) = #records(fields_before_t_in_key) / + #records(fields_before_t_in_key, t) + + The second multiplier is calculated by applying this step recursively. + + IMPLEMENTATION + This function calculates the result of application of the "recursion step" + described above for all fixed key members of a single key, accumulating set + of covered fields, selectivity, etc. + + The calculation is conducted as follows: + Lets denote #records(keypart1, ... keypartK) as n_k. We need to calculate + + n_{k1} n_{k2} + --------- * --------- * .... (3) + n_{k1-1} n_{k2-1} + + where k1,k2,... are key parts which fields were not yet marked as fixed + ( this is result of application of option b) of the recursion step for + parts of a single key). + Since it is reasonable to expect that most of the fields are not marked + as fixed, we calculate (3) as + + n_{i1} n_{i2} + (3) = n_{max_key_part} / ( --------- * --------- * .... ) + n_{i1-1} n_{i2-1} + + where i1,i2, .. are key parts that were already marked as fixed. + + In order to minimize number of expensive records_in_range calls we group + and reduce adjacent fractions. + + RETURN + Selectivity of given ROR scan. +*/ + +static double ror_scan_selectivity(const ROR_INTERSECT_INFO *info, + const ROR_SCAN_INFO *scan) +{ + double selectivity_mult= 1.0; + KEY_PART_INFO *key_part= info->param->table->key_info[scan->keynr].key_part; + uchar key_val[MAX_KEY_LENGTH+MAX_FIELD_WIDTH]; /* key values tuple */ + uchar *key_ptr= key_val; + SEL_ARG *sel_arg, *tuple_arg= NULL; + key_part_map keypart_map= 0; + bool cur_covered; + bool prev_covered= MY_TEST(bitmap_is_set(&info->covered_fields, + key_part->fieldnr - 1)); + key_range min_range; + key_range max_range; + min_range.key= key_val; + min_range.flag= HA_READ_KEY_EXACT; + max_range.key= key_val; + max_range.flag= HA_READ_AFTER_KEY; + ha_rows prev_records= info->param->table->stat_records(); + DBUG_ENTER("ror_scan_selectivity"); + + for (sel_arg= scan->sel_arg; sel_arg; + sel_arg= sel_arg->next_key_part) + { + DBUG_PRINT("info",("sel_arg step")); + cur_covered= MY_TEST(bitmap_is_set(&info->covered_fields, + key_part[sel_arg->part].fieldnr - 1)); + if (cur_covered != prev_covered) + { + /* create (part1val, ..., part{n-1}val) tuple. */ + ha_rows records; + page_range pages; + if (!tuple_arg) + { + tuple_arg= scan->sel_arg; + /* Here we use the length of the first key part */ + tuple_arg->store_min(key_part->store_length, &key_ptr, 0); + keypart_map= 1; + } + while (tuple_arg->next_key_part != sel_arg) + { + tuple_arg= tuple_arg->next_key_part; + tuple_arg->store_min(key_part[tuple_arg->part].store_length, + &key_ptr, 0); + keypart_map= (keypart_map << 1) | 1; + } + min_range.length= max_range.length= (uint) (key_ptr - key_val); + min_range.keypart_map= max_range.keypart_map= keypart_map; + records= (info->param->table->file-> + records_in_range(scan->keynr, &min_range, &max_range, &pages)); + if (cur_covered) + { + /* uncovered -> covered */ + double tmp= rows2double(records)/rows2double(prev_records); + DBUG_PRINT("info", ("Selectivity multiplier: %g", tmp)); + selectivity_mult *= tmp; + prev_records= HA_POS_ERROR; + } + else + { + /* covered -> uncovered */ + prev_records= records; + } + } + prev_covered= cur_covered; + } + if (!prev_covered) + { + double tmp= rows2double(info->param->quick_rows[scan->keynr]) / + rows2double(prev_records); + DBUG_PRINT("info", ("Selectivity multiplier: %g", tmp)); + selectivity_mult *= tmp; + } + DBUG_PRINT("info", ("Returning multiplier: %g", selectivity_mult)); + DBUG_RETURN(selectivity_mult); +} + + +/* + Check if adding a ROR scan to a ROR-intersection reduces its cost of + ROR-intersection and if yes, update parameters of ROR-intersection, + including its cost. + + SYNOPSIS + ror_intersect_add() + param Parameter from test_quick_select + info ROR-intersection structure to add the scan to. + ror_scan ROR scan info to add. + is_cpk_scan If TRUE, add the scan as CPK scan (this can be inferred + from other parameters and is passed separately only to + avoid duplicating the inference code) + + NOTES + Adding a ROR scan to ROR-intersect "makes sense" iff the cost of ROR- + intersection decreases. The cost of ROR-intersection is calculated as + follows: + + cost= SUM_i(key_scan_cost_i) + cost_of_full_rows_retrieval + + When we add a scan the first increases and the second decreases. + + cost_of_full_rows_retrieval= + (union of indexes used covers all needed fields) ? + cost_of_sweep_read(E(rows_to_retrieve), rows_in_table) : + 0 + + E(rows_to_retrieve) = #rows_in_table * ror_scan_selectivity(null, scan1) * + ror_scan_selectivity({scan1}, scan2) * ... * + ror_scan_selectivity({scan1,...}, scanN). + RETURN + TRUE ROR scan added to ROR-intersection, cost updated. + FALSE It doesn't make sense to add this ROR scan to this ROR-intersection. +*/ + +static bool ror_intersect_add(ROR_INTERSECT_INFO *info, + ROR_SCAN_INFO* ror_scan, + Json_writer_object *trace_costs, + bool is_cpk_scan) +{ + double selectivity_mult= 1.0; + + DBUG_ENTER("ror_intersect_add"); + DBUG_PRINT("info", ("Current out_rows= %g", info->out_rows)); + DBUG_PRINT("info", ("Adding scan on %s", + info->param->table->key_info[ror_scan->keynr].name.str)); + DBUG_PRINT("info", ("is_cpk_scan: %d",is_cpk_scan)); + + selectivity_mult = ror_scan_selectivity(info, ror_scan); + if (selectivity_mult == 1.0) + { + /* Don't add this scan if it doesn't improve selectivity. */ + DBUG_PRINT("info", ("The scan doesn't improve selectivity.")); + DBUG_RETURN(FALSE); + } + + info->out_rows *= selectivity_mult; + + if (is_cpk_scan) + { + /* + CPK scan is used to filter out rows. We apply filtering for + each record of every scan. Assuming 1/TIME_FOR_COMPARE_ROWID + per check this gives us: + */ + const double idx_cost= rows2double(info->index_records) / + TIME_FOR_COMPARE_ROWID; + info->index_scan_costs+= idx_cost; + trace_costs->add("index_scan_cost", idx_cost); + } + else + { + info->index_records += info->param->quick_rows[ror_scan->keynr]; + info->index_scan_costs += ror_scan->index_read_cost; + trace_costs->add("index_scan_cost", ror_scan->index_read_cost); + bitmap_union(&info->covered_fields, &ror_scan->covered_fields); + if (!info->is_covering && bitmap_is_subset(&info->param->needed_fields, + &info->covered_fields)) + { + DBUG_PRINT("info", ("ROR-intersect is covering now")); + info->is_covering= TRUE; + } + } + + info->total_cost= info->index_scan_costs; + trace_costs->add("cumulated_index_scan_cost", info->index_scan_costs); + DBUG_PRINT("info", ("info->total_cost: %g", info->total_cost)); + if (!info->is_covering) + { + double sweep_cost= get_sweep_read_cost(info->param, + double2rows(info->out_rows)); + info->total_cost+= sweep_cost; + trace_costs->add("disk_sweep_cost", sweep_cost); + DBUG_PRINT("info", ("info->total_cost= %g", info->total_cost)); + } + else + trace_costs->add("disk_sweep_cost", static_cast<longlong>(0)); + + DBUG_PRINT("info", ("New out_rows: %g", info->out_rows)); + DBUG_PRINT("info", ("New cost: %g, %scovering", info->total_cost, + info->is_covering?"" : "non-")); + DBUG_RETURN(TRUE); +} + + +/* + Get best ROR-intersection plan using non-covering ROR-intersection search + algorithm. The returned plan may be covering. + + SYNOPSIS + get_best_ror_intersect() + param Parameter from test_quick_select function. + tree Transformed restriction condition to be used to look + for ROR scans. + read_time Do not return read plans with cost > read_time. + are_all_covering [out] set to TRUE if union of all scans covers all + fields needed by the query (and it is possible to build + a covering ROR-intersection) + + NOTES + get_key_scans_params must be called before this function can be called. + + When this function is called by ROR-union construction algorithm it + assumes it is building an uncovered ROR-intersection (and thus # of full + records to be retrieved is wrong here). This is a hack. + + IMPLEMENTATION + The approximate best non-covering plan search algorithm is as follows: + + find_min_ror_intersection_scan() + { + R= select all ROR scans; + order R by (E(#records_matched) * key_record_length). + + S= first(R); -- set of scans that will be used for ROR-intersection + R= R-first(S); + min_cost= cost(S); + min_scan= make_scan(S); + while (R is not empty) + { + firstR= R - first(R); + if (!selectivity(S + firstR < selectivity(S))) + continue; + + S= S + first(R); + if (cost(S) < min_cost) + { + min_cost= cost(S); + min_scan= make_scan(S); + } + } + return min_scan; + } + + See ror_intersect_add function for ROR intersection costs. + + Special handling for Clustered PK scans + Clustered PK contains all table fields, so using it as a regular scan in + index intersection doesn't make sense: a range scan on CPK will be less + expensive in this case. + Clustered PK scan has special handling in ROR-intersection: it is not used + to retrieve rows, instead its condition is used to filter row references + we get from scans on other keys. + + RETURN + ROR-intersection table read plan + NULL if out of memory or no suitable plan found. +*/ + +static +TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree, + double read_time, + bool *are_all_covering) +{ + uint idx; + double min_cost= DBL_MAX; + DBUG_ENTER("get_best_ror_intersect"); + THD *thd= param->thd; + Json_writer_object trace_ror(thd, "analyzing_roworder_intersect"); + + if ((tree->n_ror_scans < 2) || !param->table->stat_records() || + !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_INTERSECT)) + { + if (tree->n_ror_scans < 2) + trace_ror.add("cause", "too few roworder scans"); + DBUG_RETURN(NULL); + } + + /* + Step1: Collect ROR-able SEL_ARGs and create ROR_SCAN_INFO for each of + them. Also find and save clustered PK scan if there is one. + */ + ROR_SCAN_INFO **cur_ror_scan; + ROR_SCAN_INFO *cpk_scan= NULL; + uint cpk_no; + + if (!(tree->ror_scans= (ROR_SCAN_INFO**)alloc_root(param->mem_root, + sizeof(ROR_SCAN_INFO*)* + param->keys))) + return NULL; + cpk_no= (param->table->file-> + pk_is_clustering_key(param->table->s->primary_key) ? + param->table->s->primary_key : MAX_KEY); + + for (idx= 0, cur_ror_scan= tree->ror_scans; idx < param->keys; idx++) + { + ROR_SCAN_INFO *scan; + uint key_no; + if (!tree->ror_scans_map.is_set(idx)) + continue; + key_no= param->real_keynr[idx]; + if (key_no != cpk_no && + param->table->file->index_flags(key_no,0,0) & HA_CLUSTERED_INDEX) + { + /* Ignore clustering keys */ + tree->n_ror_scans--; + continue; + } + if (!(scan= make_ror_scan(param, idx, tree->keys[idx]))) + return NULL; + if (key_no == cpk_no) + { + cpk_scan= scan; + tree->n_ror_scans--; + } + else + *(cur_ror_scan++)= scan; + } + + tree->ror_scans_end= cur_ror_scan; + DBUG_EXECUTE("info",print_ror_scans_arr(param->table, "original", + tree->ror_scans, + tree->ror_scans_end);); + /* + Ok, [ror_scans, ror_scans_end) is array of ptrs to initialized + ROR_SCAN_INFO's. + Step 2: Get best ROR-intersection using an approximate algorithm. + */ + my_qsort(tree->ror_scans, tree->n_ror_scans, sizeof(ROR_SCAN_INFO*), + (qsort_cmp)cmp_ror_scan_info); + DBUG_EXECUTE("info",print_ror_scans_arr(param->table, "ordered", + tree->ror_scans, + tree->ror_scans_end);); + + ROR_SCAN_INFO **intersect_scans; /* ROR scans used in index intersection */ + ROR_SCAN_INFO **intersect_scans_end; + if (!(intersect_scans= (ROR_SCAN_INFO**)alloc_root(param->mem_root, + sizeof(ROR_SCAN_INFO*)* + tree->n_ror_scans))) + return NULL; + intersect_scans_end= intersect_scans; + + /* Create and incrementally update ROR intersection. */ + ROR_INTERSECT_INFO *intersect, *intersect_best; + if (!(intersect= ror_intersect_init(param)) || + !(intersect_best= ror_intersect_init(param))) + return NULL; + + /* [intersect_scans,intersect_scans_best) will hold the best intersection */ + ROR_SCAN_INFO **intersect_scans_best; + cur_ror_scan= tree->ror_scans; + intersect_scans_best= intersect_scans; + Json_writer_array trace_isect_idx(thd, "intersecting_indexes"); + while (cur_ror_scan != tree->ror_scans_end && !intersect->is_covering) + { + Json_writer_object trace_idx(thd); + trace_idx.add("index", + param->table->key_info[(*cur_ror_scan)->keynr].name); + + /* S= S + first(R); R= R - first(R); */ + if (!ror_intersect_add(intersect, *cur_ror_scan, &trace_idx, FALSE)) + { + trace_idx.add("usable", false) + .add("cause", "does not reduce cost of intersect"); + cur_ror_scan++; + continue; + } + + trace_idx.add("cumulative_total_cost", intersect->total_cost) + .add("usable", true) + .add("matching_rows_now", intersect->out_rows) + .add("intersect_covering_with_this_index", intersect->is_covering); + + *(intersect_scans_end++)= *(cur_ror_scan++); + + if (intersect->total_cost < min_cost) + { + /* Local minimum found, save it */ + ror_intersect_cpy(intersect_best, intersect); + intersect_scans_best= intersect_scans_end; + min_cost = intersect->total_cost; + trace_idx.add("chosen", true); + } + else + { + trace_idx.add("chosen", false) + .add("cause", "does not reduce cost"); + } + } + trace_isect_idx.end(); + + if (intersect_scans_best == intersect_scans) + { + DBUG_PRINT("info", ("None of scans increase selectivity")); + trace_ror.add("chosen", false) + .add("cause","does not increase selectivity"); + DBUG_RETURN(NULL); + } + + DBUG_EXECUTE("info",print_ror_scans_arr(param->table, + "best ROR-intersection", + intersect_scans, + intersect_scans_best);); + + *are_all_covering= intersect->is_covering; + uint best_num= (uint)(intersect_scans_best - intersect_scans); + ror_intersect_cpy(intersect, intersect_best); + + /* + Ok, found the best ROR-intersection of non-CPK key scans. + Check if we should add a CPK scan. If the obtained ROR-intersection is + covering, it doesn't make sense to add CPK scan. + */ + Json_writer_object trace_cpk(thd, "clustered_pk"); + if (cpk_scan && !intersect->is_covering) + { + if (ror_intersect_add(intersect, cpk_scan, &trace_cpk, TRUE) && + (intersect->total_cost < min_cost)) + { + trace_cpk.add("clustered_pk_scan_added_to_intersect", true) + .add("cumulated_cost", intersect->total_cost); + intersect_best= intersect; //just set pointer here + } + else + { + trace_cpk.add("clustered_pk_added_to_intersect", false) + .add("cause", "cost"); + cpk_scan= 0; // Don't use cpk_scan + } + } + else + { + trace_cpk.add("clustered_pk_added_to_intersect", false) + .add("cause", cpk_scan ? "roworder is covering" + : "no clustered pk index"); + cpk_scan= 0; // Don't use cpk_scan + } + trace_cpk.end(); + + /* Ok, return ROR-intersect plan if we have found one */ + TRP_ROR_INTERSECT *trp= NULL; + if (min_cost < read_time && (cpk_scan || best_num > 1)) + { + if (!(trp= new (param->mem_root) TRP_ROR_INTERSECT)) + DBUG_RETURN(trp); + if (!(trp->first_scan= + (ROR_SCAN_INFO**)alloc_root(param->mem_root, + sizeof(ROR_SCAN_INFO*)*best_num))) + DBUG_RETURN(NULL); + memcpy(trp->first_scan, intersect_scans, best_num*sizeof(ROR_SCAN_INFO*)); + trp->last_scan= trp->first_scan + best_num; + trp->is_covering= intersect_best->is_covering; + trp->read_cost= intersect_best->total_cost; + /* Prevent divisons by zero */ + ha_rows best_rows = double2rows(intersect_best->out_rows); + if (!best_rows) + best_rows= 1; + set_if_smaller(param->table->opt_range_condition_rows, best_rows); + trp->records= best_rows; + trp->index_scan_costs= intersect_best->index_scan_costs; + trp->cpk_scan= cpk_scan; + DBUG_PRINT("info", ("Returning non-covering ROR-intersect plan:" + "cost %g, records %lu", + trp->read_cost, (ulong) trp->records)); + trace_ror.add("rows", trp->records) + .add("cost", trp->read_cost) + .add("covering", trp->is_covering) + .add("chosen", true); + } + else + { + trace_ror.add("chosen", false) + .add("cause", (read_time > min_cost) + ? "too few indexes to merge" + : "cost"); + } + DBUG_RETURN(trp); +} + + +/* + Get best covering ROR-intersection. + SYNOPSIS + get_best_ntersectcovering_ror_intersect() + param Parameter from test_quick_select function. + tree SEL_TREE with sets of intervals for different keys. + read_time Don't return table read plans with cost > read_time. + + RETURN + Best covering ROR-intersection plan + NULL if no plan found. + + NOTES + get_best_ror_intersect must be called for a tree before calling this + function for it. + This function invalidates tree->ror_scans member values. + + The following approximate algorithm is used: + I=set of all covering indexes + F=set of all fields to cover + S={} + + do + { + Order I by (#covered fields in F desc, + #components asc, + number of first not covered component asc); + F=F-covered by first(I); + S=S+first(I); + I=I-first(I); + } while F is not empty. +*/ + +static +TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param, + SEL_TREE *tree, + double read_time) +{ + ROR_SCAN_INFO **ror_scan_mark; + ROR_SCAN_INFO **ror_scans_end= tree->ror_scans_end; + DBUG_ENTER("get_best_covering_ror_intersect"); + + if (!optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_INTERSECT)) + DBUG_RETURN(NULL); + + for (ROR_SCAN_INFO **scan= tree->ror_scans; scan != ror_scans_end; ++scan) + (*scan)->key_components= + param->table->key_info[(*scan)->keynr].user_defined_key_parts; + + /* + Run covering-ROR-search algorithm. + Assume set I is [ror_scan .. ror_scans_end) + */ + + /*I=set of all covering indexes */ + ror_scan_mark= tree->ror_scans; + + MY_BITMAP *covered_fields= ¶m->tmp_covered_fields; + if (!covered_fields->bitmap) + covered_fields->bitmap= (my_bitmap_map*)alloc_root(param->mem_root, + param->fields_bitmap_size); + if (!covered_fields->bitmap || + my_bitmap_init(covered_fields, covered_fields->bitmap, + param->table->s->fields, FALSE)) + DBUG_RETURN(0); + bitmap_clear_all(covered_fields); + + double total_cost= 0.0f; + ha_rows records=0; + bool all_covered; + + DBUG_PRINT("info", ("Building covering ROR-intersection")); + DBUG_EXECUTE("info", print_ror_scans_arr(param->table, + "building covering ROR-I", + ror_scan_mark, ror_scans_end);); + do + { + /* + Update changed sorting info: + #covered fields, + number of first not covered component + Calculate and save these values for each of remaining scans. + */ + for (ROR_SCAN_INFO **scan= ror_scan_mark; scan != ror_scans_end; ++scan) + { + bitmap_subtract(&(*scan)->covered_fields, covered_fields); + (*scan)->used_fields_covered= + bitmap_bits_set(&(*scan)->covered_fields); + (*scan)->first_uncovered_field= + bitmap_get_first(&(*scan)->covered_fields); + } + + my_qsort(ror_scan_mark, ror_scans_end-ror_scan_mark, sizeof(ROR_SCAN_INFO*), + (qsort_cmp)cmp_ror_scan_info_covering); + + DBUG_EXECUTE("info", print_ror_scans_arr(param->table, + "remaining scans", + ror_scan_mark, ror_scans_end);); + + /* I=I-first(I) */ + total_cost += (*ror_scan_mark)->index_read_cost; + records += (*ror_scan_mark)->records; + DBUG_PRINT("info", ("Adding scan on %s", + param->table->key_info[(*ror_scan_mark)->keynr].name.str)); + if (total_cost > read_time) + DBUG_RETURN(NULL); + /* F=F-covered by first(I) */ + bitmap_union(covered_fields, &(*ror_scan_mark)->covered_fields); + all_covered= bitmap_is_subset(¶m->needed_fields, covered_fields); + } while ((++ror_scan_mark < ror_scans_end) && !all_covered); + + if (!all_covered || (ror_scan_mark - tree->ror_scans) == 1) + DBUG_RETURN(NULL); + + /* + Ok, [tree->ror_scans .. ror_scan) holds covering index_intersection with + cost total_cost. + */ + DBUG_PRINT("info", ("Covering ROR-intersect scans cost: %g", total_cost)); + DBUG_EXECUTE("info", print_ror_scans_arr(param->table, + "creating covering ROR-intersect", + tree->ror_scans, ror_scan_mark);); + + /* Add priority queue use cost. */ + total_cost += rows2double(records)* + log((double)(ror_scan_mark - tree->ror_scans)) / + (TIME_FOR_COMPARE_ROWID * M_LN2); + DBUG_PRINT("info", ("Covering ROR-intersect full cost: %g", total_cost)); + + if (total_cost > read_time) + DBUG_RETURN(NULL); + + TRP_ROR_INTERSECT *trp; + if (!(trp= new (param->mem_root) TRP_ROR_INTERSECT)) + DBUG_RETURN(trp); + uint best_num= (uint)(ror_scan_mark - tree->ror_scans); + if (!(trp->first_scan= (ROR_SCAN_INFO**)alloc_root(param->mem_root, + sizeof(ROR_SCAN_INFO*)* + best_num))) + DBUG_RETURN(NULL); + memcpy(trp->first_scan, tree->ror_scans, best_num*sizeof(ROR_SCAN_INFO*)); + trp->last_scan= trp->first_scan + best_num; + trp->is_covering= TRUE; + trp->read_cost= total_cost; + trp->records= records; + trp->cpk_scan= NULL; + set_if_smaller(param->table->opt_range_condition_rows, records); + + DBUG_PRINT("info", + ("Returning covering ROR-intersect plan: cost %g, records %lu", + trp->read_cost, (ulong) trp->records)); + DBUG_RETURN(trp); +} + + +/* + Get best "range" table read plan for given SEL_TREE. + Also update PARAM members and store ROR scans info in the SEL_TREE. + SYNOPSIS + get_key_scans_params + param parameters from test_quick_select + tree make range select for this SEL_TREE + index_read_must_be_used if TRUE, assume 'index only' option will be set + (except for clustered PK indexes) + for_range_access if TRUE the function is called to get the best range + plan for range access, not for index merge access + read_time don't create read plans with cost > read_time. + RETURN + Best range read plan + NULL if no plan found or error occurred +*/ + +static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree, + bool index_read_must_be_used, + bool for_range_access, + double read_time) +{ + uint idx, UNINIT_VAR(best_idx); + SEL_ARG *key_to_read= NULL; + ha_rows UNINIT_VAR(best_records); /* protected by key_to_read */ + uint UNINIT_VAR(best_mrr_flags), /* protected by key_to_read */ + UNINIT_VAR(best_buf_size); /* protected by key_to_read */ + TRP_RANGE* read_plan= NULL; + DBUG_ENTER("get_key_scans_params"); + THD *thd= param->thd; + /* + Note that there may be trees that have type SEL_TREE::KEY but contain no + key reads at all, e.g. tree for expression "key1 is not null" where key1 + is defined as "not null". + */ + DBUG_EXECUTE("info", print_sel_tree(param, tree, &tree->keys_map, + "tree scans");); + Json_writer_array range_scan_alt(thd, "range_scan_alternatives"); + + tree->ror_scans_map.clear_all(); + tree->n_ror_scans= 0; + tree->index_scans= 0; + if (!tree->keys_map.is_clear_all()) + { + tree->index_scans= + (INDEX_SCAN_INFO **) alloc_root(param->mem_root, + sizeof(INDEX_SCAN_INFO *) * param->keys); + } + tree->index_scans_end= tree->index_scans; + + for (idx= 0; idx < param->keys; idx++) + { + SEL_ARG *key= tree->keys[idx]; + if (key) + { + ha_rows found_records; + Cost_estimate cost; + double found_read_time; + uint mrr_flags, buf_size; + bool is_ror_scan= FALSE; + INDEX_SCAN_INFO *index_scan; + uint keynr= param->real_keynr[idx]; + if (key->type == SEL_ARG::MAYBE_KEY || + key->maybe_flag) + param->needed_reg->set_bit(keynr); + + bool read_index_only= index_read_must_be_used ? TRUE : + (bool) param->table->covering_keys.is_set(keynr); + + Json_writer_object trace_idx(thd); + trace_idx.add("index", param->table->key_info[keynr].name); + + found_records= check_quick_select(param, idx, read_index_only, key, + for_range_access, &mrr_flags, + &buf_size, &cost, &is_ror_scan); + + if (!for_range_access && !is_ror_scan && + !optimizer_flag(param->thd,OPTIMIZER_SWITCH_INDEX_MERGE_SORT_UNION)) + { + /* The scan is not a ROR-scan, just skip it */ + continue; + } + + if (found_records != HA_POS_ERROR && tree->index_scans && + (index_scan= (INDEX_SCAN_INFO *)alloc_root(param->mem_root, + sizeof(INDEX_SCAN_INFO)))) + { + Json_writer_array trace_range(thd, "ranges"); + + const KEY &cur_key= param->table->key_info[keynr]; + const KEY_PART_INFO *key_part= cur_key.key_part; + + index_scan->idx= idx; + index_scan->keynr= keynr; + index_scan->key_info= ¶m->table->key_info[keynr]; + index_scan->used_key_parts= param->max_key_parts; + index_scan->range_count= param->range_count; + index_scan->records= found_records; + index_scan->sel_arg= key; + *tree->index_scans_end++= index_scan; + + if (unlikely(thd->trace_started())) + trace_ranges(&trace_range, param, idx, key, key_part); + trace_range.end(); + + trace_idx.add("rowid_ordered", is_ror_scan) + .add("using_mrr", !(mrr_flags & HA_MRR_USE_DEFAULT_IMPL)) + .add("index_only", read_index_only) + .add("rows", found_records) + .add("cost", cost.total_cost()); + } + if ((found_records != HA_POS_ERROR) && is_ror_scan) + { + tree->n_ror_scans++; + tree->ror_scans_map.set_bit(idx); + } + if (found_records != HA_POS_ERROR && + read_time > (found_read_time= cost.total_cost())) + { + read_time= found_read_time; + best_records= found_records; + key_to_read= key; + best_idx= idx; + best_mrr_flags= mrr_flags; + best_buf_size= buf_size; + trace_idx.add("chosen", true); + } + else + { + trace_idx.add("chosen", false); + if (found_records == HA_POS_ERROR) + { + if (key->type == SEL_ARG::Type::MAYBE_KEY) + trace_idx.add("cause", "depends on unread values"); + else + trace_idx.add("cause", "unknown"); + } + else + trace_idx.add("cause", "cost"); + } + } + } + + DBUG_EXECUTE("info", print_sel_tree(param, tree, &tree->ror_scans_map, + "ROR scans");); + if (key_to_read) + { + if ((read_plan= new (param->mem_root) TRP_RANGE(key_to_read, best_idx, + best_mrr_flags))) + { + read_plan->records= best_records; + read_plan->is_ror= tree->ror_scans_map.is_set(best_idx); + read_plan->read_cost= read_time; + read_plan->mrr_buf_size= best_buf_size; + DBUG_PRINT("info", + ("Returning range plan for key %s, cost %g, records %lu", + param->table->key_info[param->real_keynr[best_idx]].name.str, + read_plan->read_cost, (ulong) read_plan->records)); + } + } + else + DBUG_PRINT("info", ("No 'range' table read plan found")); + + DBUG_RETURN(read_plan); +} + + +QUICK_SELECT_I *TRP_INDEX_MERGE::make_quick(PARAM *param, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc) +{ + QUICK_INDEX_MERGE_SELECT *quick_imerge; + QUICK_RANGE_SELECT *quick; + /* index_merge always retrieves full rows, ignore retrieve_full_rows */ + if (!(quick_imerge= new QUICK_INDEX_MERGE_SELECT(param->thd, param->table))) + return NULL; + + quick_imerge->records= records; + quick_imerge->read_time= read_cost; + for (TRP_RANGE **range_scan= range_scans; range_scan != range_scans_end; + range_scan++) + { + if (!(quick= (QUICK_RANGE_SELECT*) + ((*range_scan)->make_quick(param, FALSE, &quick_imerge->alloc)))|| + quick_imerge->push_quick_back(quick)) + { + delete quick; + delete quick_imerge; + return NULL; + } + } + return quick_imerge; +} + + +QUICK_SELECT_I *TRP_INDEX_INTERSECT::make_quick(PARAM *param, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc) +{ + QUICK_INDEX_INTERSECT_SELECT *quick_intersect; + QUICK_RANGE_SELECT *quick; + /* index_merge always retrieves full rows, ignore retrieve_full_rows */ + if (!(quick_intersect= new QUICK_INDEX_INTERSECT_SELECT(param->thd, param->table))) + return NULL; + + quick_intersect->records= records; + quick_intersect->read_time= read_cost; + quick_intersect->filtered_scans= filtered_scans; + for (TRP_RANGE **range_scan= range_scans; range_scan != range_scans_end; + range_scan++) + { + if (!(quick= (QUICK_RANGE_SELECT*) + ((*range_scan)->make_quick(param, FALSE, &quick_intersect->alloc)))|| + quick_intersect->push_quick_back(quick)) + { + delete quick; + delete quick_intersect; + return NULL; + } + } + return quick_intersect; +} + + +QUICK_SELECT_I *TRP_ROR_INTERSECT::make_quick(PARAM *param, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc) +{ + QUICK_ROR_INTERSECT_SELECT *quick_intrsect; + QUICK_RANGE_SELECT *quick; + DBUG_ENTER("TRP_ROR_INTERSECT::make_quick"); + MEM_ROOT *alloc; + + if ((quick_intrsect= + new QUICK_ROR_INTERSECT_SELECT(param->thd, param->table, + (retrieve_full_rows? (!is_covering) : + FALSE), + parent_alloc))) + { + DBUG_EXECUTE("info", print_ror_scans_arr(param->table, + "creating ROR-intersect", + first_scan, last_scan);); + alloc= parent_alloc? parent_alloc: &quick_intrsect->alloc; + for (ROR_SCAN_INFO **curr_scan= first_scan; curr_scan != last_scan; + ++curr_scan) + { + if (!(quick= get_quick_select(param, (*curr_scan)->idx, + (*curr_scan)->sel_arg, + HA_MRR_USE_DEFAULT_IMPL | HA_MRR_SORTED, + 0, alloc)) || + quick_intrsect->push_quick_back(alloc, quick)) + { + delete quick_intrsect; + DBUG_RETURN(NULL); + } + } + if (cpk_scan) + { + if (!(quick= get_quick_select(param, cpk_scan->idx, + cpk_scan->sel_arg, + HA_MRR_USE_DEFAULT_IMPL | HA_MRR_SORTED, + 0, alloc))) + { + delete quick_intrsect; + DBUG_RETURN(NULL); + } + quick->file= NULL; + quick_intrsect->cpk_quick= quick; + } + quick_intrsect->records= records; + quick_intrsect->read_time= read_cost; + } + DBUG_RETURN(quick_intrsect); +} + + +QUICK_SELECT_I *TRP_ROR_UNION::make_quick(PARAM *param, + bool retrieve_full_rows, + MEM_ROOT *parent_alloc) +{ + QUICK_ROR_UNION_SELECT *quick_roru; + TABLE_READ_PLAN **scan; + QUICK_SELECT_I *quick; + DBUG_ENTER("TRP_ROR_UNION::make_quick"); + /* + It is impossible to construct a ROR-union that will not retrieve full + rows, ignore retrieve_full_rows parameter. + */ + if ((quick_roru= new QUICK_ROR_UNION_SELECT(param->thd, param->table))) + { + for (scan= first_ror; scan != last_ror; scan++) + { + if (!(quick= (*scan)->make_quick(param, FALSE, &quick_roru->alloc)) || + quick_roru->push_quick_back(quick)) + { + delete quick_roru; + DBUG_RETURN(NULL); + } + } + quick_roru->records= records; + quick_roru->read_time= read_cost; + } + DBUG_RETURN(quick_roru); +} + + +/* + Build a SEL_TREE for <> or NOT BETWEEN predicate + + SYNOPSIS + get_ne_mm_tree() + param PARAM from SQL_SELECT::test_quick_select + cond_func item for the predicate + field field in the predicate + lt_value constant that field should be smaller + gt_value constant that field should be greaterr + + RETURN + # Pointer to tree built tree + 0 on error +*/ + +SEL_TREE *Item_bool_func::get_ne_mm_tree(RANGE_OPT_PARAM *param, + Field *field, + Item *lt_value, Item *gt_value) +{ + SEL_TREE *tree; + tree= get_mm_parts(param, field, Item_func::LT_FUNC, lt_value); + if (tree) + tree= tree_or(param, tree, get_mm_parts(param, field, Item_func::GT_FUNC, + gt_value)); + return tree; +} + + +SEL_TREE *Item_func_ne::get_func_mm_tree(RANGE_OPT_PARAM *param, + Field *field, Item *value) +{ + DBUG_ENTER("Item_func_ne::get_func_mm_tree"); + /* + If this condition is a "col1<>...", where there is a UNIQUE KEY(col1), + do not construct a SEL_TREE from it. A condition that excludes just one + row in the table is not selective (unless there are only a few rows) + */ + if (is_field_an_unique_index(param, field)) + DBUG_RETURN(NULL); + DBUG_RETURN(get_ne_mm_tree(param, field, value, value)); +} + + +SEL_TREE *Item_func_between::get_func_mm_tree(RANGE_OPT_PARAM *param, + Field *field, Item *value) +{ + SEL_TREE *tree; + DBUG_ENTER("Item_func_between::get_func_mm_tree"); + if (!value) + { + if (negated) + { + tree= get_ne_mm_tree(param, field, args[1], args[2]); + } + else + { + tree= get_mm_parts(param, field, Item_func::GE_FUNC, args[1]); + if (tree) + { + tree= tree_and(param, tree, get_mm_parts(param, field, + Item_func::LE_FUNC, + args[2])); + } + } + } + else + { + tree= get_mm_parts(param, field, + (negated ? + (value == (Item*)1 ? Item_func::GT_FUNC : + Item_func::LT_FUNC): + (value == (Item*)1 ? Item_func::LE_FUNC : + Item_func::GE_FUNC)), + args[0]); + } + DBUG_RETURN(tree); +} + + +SEL_TREE *Item_func_in::get_func_mm_tree(RANGE_OPT_PARAM *param, + Field *field, Item *value) +{ + SEL_TREE *tree= 0; + DBUG_ENTER("Item_func_in::get_func_mm_tree"); + /* + Array for IN() is constructed when all values have the same result + type. Tree won't be built for values with different result types, + so we check it here to avoid unnecessary work. + */ + if (!arg_types_compatible) + DBUG_RETURN(0); + + if (negated) + { + if (array && array->type_handler()->result_type() != ROW_RESULT) + { + /* + We get here for conditions in form "t.key NOT IN (c1, c2, ...)", + where c{i} are constants. Our goal is to produce a SEL_TREE that + represents intervals: + + ($MIN<t.key<c1) OR (c1<t.key<c2) OR (c2<t.key<c3) OR ... (*) + + where $MIN is either "-inf" or NULL. + + The most straightforward way to produce it is to convert NOT IN + into "(t.key != c1) AND (t.key != c2) AND ... " and let the range + analyzer to build SEL_TREE from that. The problem is that the + range analyzer will use O(N^2) memory (which is probably a bug), + and people do use big NOT IN lists (e.g. see BUG#15872, BUG#21282), + will run out of memory. + + Another problem with big lists like (*) is that a big list is + unlikely to produce a good "range" access, while considering that + range access will require expensive CPU calculations (and for + MyISAM even index accesses). In short, big NOT IN lists are rarely + worth analyzing. + + Considering the above, we'll handle NOT IN as follows: + * if the number of entries in the NOT IN list is less than + NOT_IN_IGNORE_THRESHOLD, construct the SEL_TREE (*) manually. + * Otherwise, don't produce a SEL_TREE. + */ +#define NOT_IN_IGNORE_THRESHOLD 1000 + MEM_ROOT *tmp_root= param->mem_root; + param->thd->mem_root= param->old_root; + /* + Create one Item_type constant object. We'll need it as + get_mm_parts only accepts constant values wrapped in Item_Type + objects. + We create the Item on param->mem_root which points to + per-statement mem_root (while thd->mem_root is currently pointing + to mem_root local to range optimizer). + */ + Item *value_item= array->create_item(param->thd); + param->thd->mem_root= tmp_root; + + if (array->count > NOT_IN_IGNORE_THRESHOLD || !value_item) + DBUG_RETURN(0); + + /* + if this is a "col1 NOT IN (...)", and there is a UNIQUE KEY(col1), do + not constuct a SEL_TREE from it. The rationale is as follows: + - if there are only a few constants, this condition is not selective + (unless the table is also very small in which case we won't gain + anything) + - if there are a lot of constants, the overhead of building and + processing enormous range list is not worth it. + */ + if (is_field_an_unique_index(param, field)) + DBUG_RETURN(0); + + /* Get a SEL_TREE for "(-inf|NULL) < X < c_0" interval. */ + uint i=0; + do + { + array->value_to_item(i, value_item); + tree= get_mm_parts(param, field, Item_func::LT_FUNC, value_item); + if (!tree) + break; + i++; + } while (i < array->count && tree->type == SEL_TREE::IMPOSSIBLE); + + if (!tree || tree->type == SEL_TREE::IMPOSSIBLE) + { + /* We get here in cases like "t.unsigned NOT IN (-1,-2,-3) */ + DBUG_RETURN(NULL); + } + SEL_TREE *tree2; + for (; i < array->used_count; i++) + { + if (array->compare_elems(i, i-1)) + { + /* Get a SEL_TREE for "-inf < X < c_i" interval */ + array->value_to_item(i, value_item); + tree2= get_mm_parts(param, field, Item_func::LT_FUNC, value_item); + if (!tree2) + { + tree= NULL; + break; + } + + /* Change all intervals to be "c_{i-1} < X < c_i" */ + for (uint idx= 0; idx < param->keys; idx++) + { + SEL_ARG *new_interval, *last_val; + if (((new_interval= tree2->keys[idx])) && + (tree->keys[idx]) && + ((last_val= tree->keys[idx]->last()))) + { + new_interval->min_value= last_val->max_value; + new_interval->min_flag= NEAR_MIN; + + /* + If the interval is over a partial keypart, the + interval must be "c_{i-1} <= X < c_i" instead of + "c_{i-1} < X < c_i". Reason: + + Consider a table with a column "my_col VARCHAR(3)", + and an index with definition + "INDEX my_idx my_col(1)". If the table contains rows + with my_col values "f" and "foo", the index will not + distinguish the two rows. + + Note that tree_or() below will effectively merge + this range with the range created for c_{i-1} and + we'll eventually end up with only one range: + "NULL < X". + + Partitioning indexes are never partial. + */ + if (param->using_real_indexes) + { + const KEY key= + param->table->key_info[param->real_keynr[idx]]; + const KEY_PART_INFO *kpi= key.key_part + new_interval->part; + + if (kpi->key_part_flag & HA_PART_KEY_SEG) + new_interval->min_flag= 0; + } + } + } + /* + The following doesn't try to allocate memory so no need to + check for NULL. + */ + tree= tree_or(param, tree, tree2); + } + } + + if (tree && tree->type != SEL_TREE::IMPOSSIBLE) + { + /* + Get the SEL_TREE for the last "c_last < X < +inf" interval + (value_item cotains c_last already) + */ + tree2= get_mm_parts(param, field, Item_func::GT_FUNC, value_item); + tree= tree_or(param, tree, tree2); + } + } + else + { + tree= get_ne_mm_tree(param, field, args[1], args[1]); + if (tree) + { + Item **arg, **end; + for (arg= args + 2, end= arg + arg_count - 2; arg < end ; arg++) + { + tree= tree_and(param, tree, get_ne_mm_tree(param, field, + *arg, *arg)); + } + } + } + } + else + { + tree= get_mm_parts(param, field, Item_func::EQ_FUNC, args[1]); + if (tree) + { + Item **arg, **end; + for (arg= args + 2, end= arg + arg_count - 2; + arg < end ; arg++) + { + tree= tree_or(param, tree, get_mm_parts(param, field, + Item_func::EQ_FUNC, *arg)); + } + } + } + DBUG_RETURN(tree); +} + + +/* + The structure Key_col_info is purely auxiliary and is used + only in the method Item_func_in::get_func_row_mm_tree +*/ +struct Key_col_info { + Field *field; /* If != NULL the column can be used for keys */ + cmp_item *comparator; /* If != 0 the column can be evaluated */ +}; + +/** + Build SEL_TREE for the IN predicate whose arguments are rows + + @param param PARAM from SQL_SELECT::test_quick_select + @param key_row First operand of the IN predicate + + @note + The function builds a SEL_TREE for in IN predicate in the case + when the predicate uses row arguments. First the function + detects among the components of the key_row (c[1],...,c[n]) taken + from in the left part the predicate those that can be usable + for building SEL_TREE (c[i1],...,c[ik]). They have to contain + items whose real items are field items referring to the current + table or equal to the items referring to the current table. + For the remaining components of the row it checks whether they + can be evaluated. The result of the analysis is put into the + array of structures of the type Key_row_col_info. + + After this the function builds the SEL_TREE for the following + formula that can be inferred from the given IN predicate: + c[i11]=a[1][i11] AND ... AND c[i1k1]=a[1][i1k1] + OR + ... + OR + c[im1]=a[m][im1] AND ... AND c[imkm]=a[m][imkm]. + Here a[1],...,a[m] are all arguments of the IN predicate from + the right part and for each j ij1,...,ijkj is a subset of + i1,...,ik such that a[j][ij1],...,a[j][ijkj] can be evaluated. + + If for some j there no a[j][i1],...,a[j][ik] can be evaluated + then no SEL_TREE can be built for this predicate and the + function immediately returns 0. + + If for some j by using evaluated values of key_row it can be + proven that c[ij1]=a[j][ij1] AND ... AND c[ijkj]=a[j][ijkj] + is always FALSE then this disjunct is omitted. + + @returns + the built SEL_TREE if it can be constructed + 0 - otherwise. +*/ + +SEL_TREE *Item_func_in::get_func_row_mm_tree(RANGE_OPT_PARAM *param, + Item_row *key_row) +{ + DBUG_ENTER("Item_func_in::get_func_row_mm_tree"); + + if (negated) + DBUG_RETURN(0); + + SEL_TREE *res_tree= 0; + uint used_key_cols= 0; + uint col_comparators= 0; + table_map param_comp= ~(param->prev_tables | param->read_tables | + param->current_table); + uint row_cols= key_row->cols(); + Dynamic_array <Key_col_info> key_cols_info(row_cols); + cmp_item_row *row_cmp_item; + + if (array) + { + in_row *row= static_cast<in_row*>(array); + row_cmp_item= static_cast<cmp_item_row*>(row->get_cmp_item()); + } + else + { + DBUG_ASSERT(get_comparator_type_handler(0) == &type_handler_row); + row_cmp_item= static_cast<cmp_item_row*>(get_comparator_cmp_item(0)); + } + DBUG_ASSERT(row_cmp_item); + + Item **key_col_ptr= key_row->addr(0); + for(uint i= 0; i < row_cols; i++, key_col_ptr++) + { + Key_col_info key_col_info= {0, NULL}; + Item *key_col= *key_col_ptr; + if (key_col->real_item()->type() == Item::FIELD_ITEM) + { + /* + The i-th component of key_row can be used for key access if + key_col->real_item() points to a field of the current table or + if it is equal to a field item pointing to such a field. + */ + Item_field *col_field_item= (Item_field *) (key_col->real_item()); + Field *key_col_field= col_field_item->field; + if (key_col_field->table->map != param->current_table) + { + Item_equal *item_equal= col_field_item->item_equal; + if (item_equal) + { + Item_equal_fields_iterator it(*item_equal); + while (it++) + { + key_col_field= it.get_curr_field(); + if (key_col_field->table->map == param->current_table) + break; + } + } + } + if (key_col_field->table->map == param->current_table) + { + key_col_info.field= key_col_field; + used_key_cols++; + } + } + else if (!(key_col->used_tables() & (param_comp | param->current_table)) + && !key_col->is_expensive()) + { + /* The i-th component of key_row can be evaluated */ + + /* See the comment in Item::get_mm_tree_for_const */ + MEM_ROOT *tmp_root= param->mem_root; + param->thd->mem_root= param->old_root; + + key_col->bring_value(); + key_col_info.comparator= row_cmp_item->get_comparator(i); + DBUG_ASSERT(key_col_info.comparator); + key_col_info.comparator->store_value(key_col); + col_comparators++; + + param->thd->mem_root= tmp_root; + } + key_cols_info.push(key_col_info); + } + + if (!used_key_cols) + DBUG_RETURN(0); + + uint omitted_tuples= 0; + Item **arg_start= arguments() + 1; + Item **arg_end= arg_start + argument_count() - 1; + for (Item **arg= arg_start ; arg < arg_end; arg++) + { + uint i; + + /* + First check whether the disjunct constructed for *arg + is really needed + */ + Item_row *arg_tuple= (Item_row *) (*arg); + if (col_comparators) + { + MEM_ROOT *tmp_root= param->mem_root; + param->thd->mem_root= param->old_root; + for (i= 0; i < row_cols; i++) + { + Key_col_info *key_col_info= &key_cols_info.at(i); + if (key_col_info->comparator) + { + Item *arg_col= arg_tuple->element_index(i); + if (!(arg_col->used_tables() & (param_comp | param->current_table)) && + !arg_col->is_expensive() && + key_col_info->comparator->cmp(arg_col)) + { + omitted_tuples++; + break; + } + } + } + param->thd->mem_root= tmp_root; + if (i < row_cols) + continue; + } + + /* The disjunct for *arg is needed: build it. */ + SEL_TREE *and_tree= 0; + Item **arg_col_ptr= arg_tuple->addr(0); + for (uint i= 0; i < row_cols; i++, arg_col_ptr++) + { + Key_col_info *key_col_info= &key_cols_info.at(i); + if (!key_col_info->field) + continue; + Item *arg_col= *arg_col_ptr; + if (!(arg_col->used_tables() & (param_comp | param->current_table)) && + !arg_col->is_expensive()) + { + and_tree= tree_and(param, and_tree, + get_mm_parts(param, + key_col_info->field, + Item_func::EQ_FUNC, + arg_col->real_item())); + } + } + if (!and_tree) + { + res_tree= 0; + break; + } + /* Join the disjunct the the OR tree that is being constructed */ + res_tree= !res_tree ? and_tree : tree_or(param, res_tree, and_tree); + } + if (omitted_tuples == argument_count() - 1) + { + /* It's turned out that all disjuncts are always FALSE */ + res_tree= new (param->mem_root) SEL_TREE(SEL_TREE::IMPOSSIBLE, + param->mem_root, param->keys); + } + DBUG_RETURN(res_tree); +} + + +/* + Build conjunction of all SEL_TREEs for a simple predicate applying equalities + + SYNOPSIS + get_full_func_mm_tree() + param PARAM from SQL_SELECT::test_quick_select + field_item field in the predicate + value constant in the predicate (or a field already read from + a table in the case of dynamic range access) + (for BETWEEN it contains the number of the field argument, + for IN it's always 0) + inv TRUE <> NOT cond_func is considered + (makes sense only when cond_func is BETWEEN or IN) + + DESCRIPTION + For a simple SARGable predicate of the form (f op c), where f is a field and + c is a constant, the function builds a conjunction of all SEL_TREES that can + be obtained by the substitution of f for all different fields equal to f. + + NOTES + If the WHERE condition contains a predicate (fi op c), + then not only SELL_TREE for this predicate is built, but + the trees for the results of substitution of fi for + each fj belonging to the same multiple equality as fi + are built as well. + E.g. for WHERE t1.a=t2.a AND t2.a > 10 + a SEL_TREE for t2.a > 10 will be built for quick select from t2 + and + a SEL_TREE for t1.a > 10 will be built for quick select from t1. + + A BETWEEN predicate of the form (fi [NOT] BETWEEN c1 AND c2) is treated + in a similar way: we build a conjuction of trees for the results + of all substitutions of fi for equal fj. + Yet a predicate of the form (c BETWEEN f1i AND f2i) is processed + differently. It is considered as a conjuction of two SARGable + predicates (f1i <= c) and (f2i <=c) and the function get_full_func_mm_tree + is called for each of them separately producing trees for + AND j (f1j <=c ) and AND j (f2j <= c) + After this these two trees are united in one conjunctive tree. + It's easy to see that the same tree is obtained for + AND j,k (f1j <=c AND f2k<=c) + which is equivalent to + AND j,k (c BETWEEN f1j AND f2k). + The validity of the processing of the predicate (c NOT BETWEEN f1i AND f2i) + which equivalent to (f1i > c OR f2i < c) is not so obvious. Here the + function get_full_func_mm_tree is called for (f1i > c) and (f2i < c) + producing trees for AND j (f1j > c) and AND j (f2j < c). Then this two + trees are united in one OR-tree. The expression + (AND j (f1j > c) OR AND j (f2j < c) + is equivalent to the expression + AND j,k (f1j > c OR f2k < c) + which is just a translation of + AND j,k (c NOT BETWEEN f1j AND f2k) + + In the cases when one of the items f1, f2 is a constant c1 we do not create + a tree for it at all. It works for BETWEEN predicates but does not + work for NOT BETWEEN predicates as we have to evaluate the expression + with it. If it is TRUE then the other tree can be completely ignored. + We do not do it now and no trees are built in these cases for + NOT BETWEEN predicates. + + As to IN predicates only ones of the form (f IN (c1,...,cn)), + where f1 is a field and c1,...,cn are constant, are considered as + SARGable. We never try to narrow the index scan using predicates of + the form (c IN (c1,...,f,...,cn)). + + RETURN + Pointer to the tree representing the built conjunction of SEL_TREEs +*/ + +SEL_TREE *Item_bool_func::get_full_func_mm_tree(RANGE_OPT_PARAM *param, + Item_field *field_item, + Item *value) +{ + DBUG_ENTER("Item_bool_func::get_full_func_mm_tree"); + SEL_TREE *tree= 0; + SEL_TREE *ftree= 0; + table_map ref_tables= 0; + table_map param_comp= ~(param->prev_tables | param->read_tables | + param->current_table); + + for (uint i= 0; i < arg_count; i++) + { + Item *arg= arguments()[i]->real_item(); + if (arg != field_item) + ref_tables|= arg->used_tables(); + } + Field *field= field_item->field; + if (!((ref_tables | field->table->map) & param_comp)) + ftree= get_func_mm_tree(param, field, value); + Item_equal *item_equal= field_item->item_equal; + if (item_equal) + { + Item_equal_fields_iterator it(*item_equal); + while (it++) + { + Field *f= it.get_curr_field(); + if (field->eq(f)) + continue; + if (!((ref_tables | f->table->map) & param_comp)) + { + tree= get_func_mm_tree(param, f, value); + ftree= !ftree ? tree : tree_and(param, ftree, tree); + } + } + } + + DBUG_RETURN(ftree); +} + + +/* + make a select tree of all keys in condition + + @param param Context + @param cond INOUT condition to perform range analysis on. + + @detail + Range analysis may infer that some conditions are never true. + - If the condition is never true, SEL_TREE(type=IMPOSSIBLE) is returned + - if parts of condition are never true, the function may remove these parts + from the condition 'cond'. Sometimes, this will cause the condition to + be substituted for something else. + + + @return + NULL - Could not infer anything from condition cond. + SEL_TREE with type=IMPOSSIBLE - condition can never be true. +*/ +SEL_TREE *Item_cond_and::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item_cond_and::get_mm_tree"); + SEL_TREE *tree= NULL; + List_iterator<Item> li(*argument_list()); + Item *item; + while ((item= li++)) + { + SEL_TREE *new_tree= li.ref()[0]->get_mm_tree(param,li.ref()); + if (param->statement_should_be_aborted()) + DBUG_RETURN(NULL); + tree= tree_and(param, tree, new_tree); + if (tree && tree->type == SEL_TREE::IMPOSSIBLE) + { + /* + Do not remove 'item' from 'cond'. We return a SEL_TREE::IMPOSSIBLE + and that is sufficient for the caller to see that the whole + condition is never true. + */ + break; + } + } + DBUG_RETURN(tree); +} + + +SEL_TREE *Item_cond::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item_cond::get_mm_tree"); + List_iterator<Item> li(*argument_list()); + bool replace_cond= false; + Item *replacement_item= li++; + SEL_TREE *tree= li.ref()[0]->get_mm_tree(param, li.ref()); + if (param->statement_should_be_aborted()) + DBUG_RETURN(NULL); + if (tree) + { + if (tree->type == SEL_TREE::IMPOSSIBLE && + param->remove_false_where_parts) + { + /* See the other li.remove() call below */ + li.remove(); + if (argument_list()->elements <= 1) + replace_cond= true; + } + + Item *item; + while ((item= li++)) + { + SEL_TREE *new_tree= li.ref()[0]->get_mm_tree(param, li.ref()); + if (new_tree == NULL || param->statement_should_be_aborted()) + DBUG_RETURN(NULL); + tree= tree_or(param, tree, new_tree); + if (tree == NULL || tree->type == SEL_TREE::ALWAYS) + { + replacement_item= *li.ref(); + break; + } + + if (new_tree && new_tree->type == SEL_TREE::IMPOSSIBLE && + param->remove_false_where_parts) + { + /* + This is a condition in form + + cond = item1 OR ... OR item_i OR ... itemN + + and item_i produces SEL_TREE(IMPOSSIBLE). We should remove item_i + from cond. This may cause 'cond' to become a degenerate, + one-way OR. In that case, we replace 'cond' with the remaining + item_i. + */ + li.remove(); + if (argument_list()->elements <= 1) + replace_cond= true; + } + else + replacement_item= *li.ref(); + } + + if (replace_cond) + *cond_ptr= replacement_item; + } + DBUG_RETURN(tree); +} + + +SEL_TREE *Item::get_mm_tree_for_const(RANGE_OPT_PARAM *param) +{ + DBUG_ENTER("get_mm_tree_for_const"); + if (is_expensive()) + DBUG_RETURN(0); + /* + During the cond->val_int() evaluation we can come across a subselect + item which may allocate memory on the thd->mem_root and assumes + all the memory allocated has the same life span as the subselect + item itself. So we have to restore the thread's mem_root here. + */ + MEM_ROOT *tmp_root= param->mem_root; + param->thd->mem_root= param->old_root; + SEL_TREE *tree; + + const SEL_TREE::Type type= val_int()? SEL_TREE::ALWAYS: SEL_TREE::IMPOSSIBLE; + param->thd->mem_root= tmp_root; + + tree= new (tmp_root) SEL_TREE(type, tmp_root, param->keys); + DBUG_RETURN(tree); +} + + +SEL_TREE *Item::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item::get_mm_tree"); + if (const_item()) + DBUG_RETURN(get_mm_tree_for_const(param)); + + /* + Here we have a not-constant non-function Item. + + Item_field should not appear, as normalize_cond() replaces + "WHERE field" to "WHERE field<>0". + + Item_exists_subselect is possible, e.g. in this query: + SELECT id, st FROM t1 + WHERE st IN ('GA','FL') AND EXISTS (SELECT 1 FROM t2 WHERE t2.id=t1.id) + GROUP BY id; + */ + table_map ref_tables= used_tables(); + if ((ref_tables & param->current_table) || + (ref_tables & ~(param->prev_tables | param->read_tables))) + DBUG_RETURN(0); + DBUG_RETURN(new (param->mem_root) SEL_TREE(SEL_TREE::MAYBE, param->mem_root, + param->keys)); +} + + +SEL_TREE * +Item_func_between::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item_func_between::get_mm_tree"); + if (const_item()) + DBUG_RETURN(get_mm_tree_for_const(param)); + + SEL_TREE *tree= 0; + SEL_TREE *ftree= 0; + + if (arguments()[0]->real_item()->type() == Item::FIELD_ITEM) + { + Item_field *field_item= (Item_field*) (arguments()[0]->real_item()); + ftree= get_full_func_mm_tree(param, field_item, NULL); + } + + /* + Concerning the code below see the NOTES section in + the comments for the function get_full_func_mm_tree() + */ + for (uint i= 1 ; i < arg_count ; i++) + { + if (arguments()[i]->real_item()->type() == Item::FIELD_ITEM) + { + Item_field *field_item= (Item_field*) (arguments()[i]->real_item()); + SEL_TREE *tmp= get_full_func_mm_tree(param, field_item, + (Item*)(intptr) i); + if (negated) + { + tree= !tree ? tmp : tree_or(param, tree, tmp); + if (tree == NULL) + break; + } + else + tree= tree_and(param, tree, tmp); + } + else if (negated) + { + tree= 0; + break; + } + } + + ftree= tree_and(param, ftree, tree); + DBUG_RETURN(ftree); +} + + +SEL_TREE *Item_func_in::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item_func_in::get_mm_tree"); + if (const_item()) + DBUG_RETURN(get_mm_tree_for_const(param)); + + SEL_TREE *tree= 0; + switch (key_item()->real_item()->type()) { + case Item::FIELD_ITEM: + tree= get_full_func_mm_tree(param, + (Item_field*) (key_item()->real_item()), + NULL); + break; + case Item::ROW_ITEM: + tree= get_func_row_mm_tree(param, + (Item_row *) (key_item()->real_item())); + break; + default: + DBUG_RETURN(0); + } + DBUG_RETURN(tree); +} + + +SEL_TREE *Item_equal::get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr) +{ + DBUG_ENTER("Item_equal::get_mm_tree"); + if (const_item()) + DBUG_RETURN(get_mm_tree_for_const(param)); + + SEL_TREE *tree= 0; + SEL_TREE *ftree= 0; + + Item *value; + if (!(value= get_const()) || value->is_expensive()) + DBUG_RETURN(0); + + Item_equal_fields_iterator it(*this); + table_map ref_tables= value->used_tables(); + table_map param_comp= ~(param->prev_tables | param->read_tables | + param->current_table); + while (it++) + { + Field *field= it.get_curr_field(); + if (!((ref_tables | field->table->map) & param_comp)) + { + tree= get_mm_parts(param, field, Item_func::EQ_FUNC, value); + ftree= !ftree ? tree : tree_and(param, ftree, tree); + } + } + + DBUG_RETURN(ftree); +} + + +/* + @brief + Check if there is an one-segment unique key that matches the field exactly + + @detail + In the future we could also add "almost unique" indexes where any value is + present only in a few rows (but necessarily exactly one row) +*/ +static bool is_field_an_unique_index(RANGE_OPT_PARAM *param, Field *field) +{ + DBUG_ENTER("is_field_an_unique_index"); + + // The check for using_real_indexes is there because of the heuristics + // this function is used for. + if (param->using_real_indexes) + { + key_map::Iterator it(field->key_start); + uint key_no; + while ((key_no= it++) != key_map::Iterator::BITMAP_END) + { + KEY *key_info= &field->table->key_info[key_no]; + if (key_info->user_defined_key_parts == 1 && + (key_info->flags & HA_NOSAME)) + { + DBUG_RETURN(true); + } + } + } + DBUG_RETURN(false); +} + + +SEL_TREE * +Item_bool_func::get_mm_parts(RANGE_OPT_PARAM *param, Field *field, + Item_func::Functype type, Item *value) +{ + DBUG_ENTER("get_mm_parts"); + if (field->table != param->table) + DBUG_RETURN(0); + + KEY_PART *key_part = param->key_parts; + KEY_PART *end = param->key_parts_end; + SEL_TREE *tree=0; + table_map value_used_tables= 0; + if (value && + (value_used_tables= value->used_tables()) & + ~(param->prev_tables | param->read_tables)) + DBUG_RETURN(0); + for (; key_part != end ; key_part++) + { + if (field->eq(key_part->field)) + { + SEL_ARG *sel_arg=0; + if (!tree && !(tree=new (param->thd->mem_root) SEL_TREE(param->mem_root, + param->keys))) + DBUG_RETURN(0); // OOM + if (!value || !(value_used_tables & ~param->read_tables)) + { + /* + We need to restore the runtime mem_root of the thread in this + function because it evaluates the value of its argument, while + the argument can be any, e.g. a subselect. The subselect + items, in turn, assume that all the memory allocated during + the evaluation has the same life span as the item itself. + TODO: opt_range.cc should not reset thd->mem_root at all. + */ + MEM_ROOT *tmp_root= param->mem_root; + param->thd->mem_root= param->old_root; + sel_arg= get_mm_leaf(param, key_part->field, key_part, type, value); + param->thd->mem_root= tmp_root; + + if (!sel_arg) + continue; + if (sel_arg->type == SEL_ARG::IMPOSSIBLE) + { + tree->type=SEL_TREE::IMPOSSIBLE; + DBUG_RETURN(tree); + } + } + else + { + // This key may be used later + if (!(sel_arg= new SEL_ARG(SEL_ARG::MAYBE_KEY))) + DBUG_RETURN(0); // OOM + } + sel_arg->part=(uchar) key_part->part; + sel_arg->max_part_no= sel_arg->part+1; + tree->keys[key_part->key]=sel_add(tree->keys[key_part->key],sel_arg); + tree->keys_map.set_bit(key_part->key); + } + } + + if (tree && tree->merges.is_empty() && tree->keys_map.is_clear_all()) + tree= NULL; + DBUG_RETURN(tree); +} + + +SEL_ARG * +Item_func_null_predicate::get_mm_leaf(RANGE_OPT_PARAM *param, + Field *field, KEY_PART *key_part, + Item_func::Functype type, + Item *value) +{ + MEM_ROOT *alloc= param->mem_root; + DBUG_ENTER("Item_func_null_predicate::get_mm_leaf"); + DBUG_ASSERT(!value); + /* + No check for field->table->maybe_null. It's perfecly fine to use range + access for cases like + + SELECT * FROM t1 LEFT JOIN t2 ON t2.key IS [NOT] NULL + + ON expression is evaluated before considering NULL-complemented rows, so + IS [NOT] NULL has regular semantics. + */ + if (!field->real_maybe_null()) + DBUG_RETURN(type == ISNULL_FUNC ? &null_element : NULL); + SEL_ARG *tree; + if (!(tree= new (alloc) SEL_ARG(field, is_null_string, is_null_string))) + DBUG_RETURN(0); + if (type == Item_func::ISNOTNULL_FUNC) + { + tree->min_flag=NEAR_MIN; /* IS NOT NULL -> X > NULL */ + tree->max_flag=NO_MAX_RANGE; + } + DBUG_RETURN(tree); +} + + +SEL_ARG * +Item_func_like::get_mm_leaf(RANGE_OPT_PARAM *param, + Field *field, KEY_PART *key_part, + Item_func::Functype type, Item *value) +{ + DBUG_ENTER("Item_func_like::get_mm_leaf"); + DBUG_ASSERT(value); + + if (key_part->image_type != Field::itRAW) + DBUG_RETURN(0); + + if (param->using_real_indexes && + !field->optimize_range(param->real_keynr[key_part->key], + key_part->part)) + DBUG_RETURN(0); + + if (field->result_type() == STRING_RESULT && + field->charset() != compare_collation()) + DBUG_RETURN(0); + + StringBuffer<MAX_FIELD_WIDTH> tmp(value->collation.collation); + String *res; + + if (!(res= value->val_str(&tmp))) + DBUG_RETURN(&null_element); + + if (field->cmp_type() != STRING_RESULT || + field->type_handler() == &type_handler_enum || + field->type_handler() == &type_handler_set) + DBUG_RETURN(0); + + /* + TODO: + Check if this was a function. This should have be optimized away + in the sql_select.cc + */ + if (res != &tmp) + { + tmp.copy(*res); // Get own copy + res= &tmp; + } + + uint maybe_null= (uint) field->real_maybe_null(); + size_t field_length= field->pack_length() + maybe_null; + size_t offset= maybe_null; + size_t length= key_part->store_length; + + if (length != key_part->length + maybe_null) + { + /* key packed with length prefix */ + offset+= HA_KEY_BLOB_LENGTH; + field_length= length - HA_KEY_BLOB_LENGTH; + } + else + { + if (unlikely(length < field_length)) + { + /* + This can only happen in a table created with UNIREG where one key + overlaps many fields + */ + length= field_length; + } + else + field_length= length; + } + length+= offset; + uchar *min_str,*max_str; + if (!(min_str= (uchar*) alloc_root(param->mem_root, length*2))) + DBUG_RETURN(0); + max_str= min_str + length; + if (maybe_null) + max_str[0]= min_str[0]=0; + + size_t min_length, max_length; + field_length-= maybe_null; + if (field->charset()->like_range(res->ptr(), res->length(), + escape, wild_one, wild_many, + field_length, + (char*) min_str + offset, + (char*) max_str + offset, + &min_length, &max_length)) + DBUG_RETURN(0); // Can't optimize with LIKE + + if (offset != maybe_null) // BLOB or VARCHAR + { + int2store(min_str + maybe_null, min_length); + int2store(max_str + maybe_null, max_length); + } + SEL_ARG *tree= new (param->mem_root) SEL_ARG(field, min_str, max_str); + DBUG_RETURN(tree); +} + + +SEL_ARG * +Item_bool_func::get_mm_leaf(RANGE_OPT_PARAM *param, + Field *field, KEY_PART *key_part, + Item_func::Functype functype, Item *value) +{ + DBUG_ENTER("Item_bool_func::get_mm_leaf"); + DBUG_ASSERT(value); // IS NULL and IS NOT NULL are handled separately + if (key_part->image_type != Field::itRAW) + DBUG_RETURN(0); // e.g. SPATIAL index + DBUG_RETURN(field->get_mm_leaf(param, key_part, this, + functype_to_scalar_comparison_op(functype), + value)); +} + + +bool Field::can_optimize_scalar_range(const RANGE_OPT_PARAM *param, + const KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, + const Item *value) const +{ + bool is_eq_func= op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL; + if ((param->using_real_indexes && + !optimize_range(param->real_keynr[key_part->key], + key_part->part) && !is_eq_func) || + !can_optimize_range(cond, value, is_eq_func)) + return false; + return true; +} + + +uchar *Field::make_key_image(MEM_ROOT *mem_root, const KEY_PART *key_part) +{ + DBUG_ENTER("Field::make_key_image"); + uint maybe_null= (uint) real_maybe_null(); + uchar *str; + if (!(str= (uchar*) alloc_root(mem_root, key_part->store_length + 1))) + DBUG_RETURN(0); + if (maybe_null) + *str= (uchar) is_real_null(); // Set to 1 if null + get_key_image(str + maybe_null, key_part->length, key_part->image_type); + DBUG_RETURN(str); +} + + +SEL_ARG *Field::stored_field_make_mm_leaf_truncated(RANGE_OPT_PARAM *param, + scalar_comparison_op op, + Item *value) +{ + DBUG_ENTER("Field::stored_field_make_mm_leaf_truncated"); + if ((op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL) && + value->result_type() == item_cmp_type(result_type(), + value->result_type())) + DBUG_RETURN(new (param->mem_root) SEL_ARG_IMPOSSIBLE(this)); + /* + TODO: We should return trees of the type SEL_ARG::IMPOSSIBLE + for the cases like int_field > 999999999999999999999999 as well. + */ + DBUG_RETURN(0); +} + + +SEL_ARG *Field_num::get_mm_leaf(RANGE_OPT_PARAM *prm, KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, Item *value) +{ + DBUG_ENTER("Field_num::get_mm_leaf"); + if (!can_optimize_scalar_range(prm, key_part, cond, op, value)) + DBUG_RETURN(0); + int err= value->save_in_field_no_warnings(this, 1); + if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0) + DBUG_RETURN(&null_element); + if (err > 0 && cmp_type() != value->result_type()) + DBUG_RETURN(stored_field_make_mm_leaf_truncated(prm, op, value)); + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); +} + + +SEL_ARG *Field_temporal::get_mm_leaf(RANGE_OPT_PARAM *prm, KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, Item *value) +{ + DBUG_ENTER("Field_temporal::get_mm_leaf"); + if (!can_optimize_scalar_range(prm, key_part, cond, op, value)) + DBUG_RETURN(0); + int err= value->save_in_field_no_warnings(this, 1); + if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0) + DBUG_RETURN(&null_element); + if (err > 0) + DBUG_RETURN(stored_field_make_mm_leaf_truncated(prm, op, value)); + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); +} + + +SEL_ARG *Field_date_common::get_mm_leaf(RANGE_OPT_PARAM *prm, + KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, + Item *value) +{ + DBUG_ENTER("Field_date_common::get_mm_leaf"); + if (!can_optimize_scalar_range(prm, key_part, cond, op, value)) + DBUG_RETURN(0); + int err= value->save_in_field_no_warnings(this, 1); + if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0) + DBUG_RETURN(&null_element); + if (err > 0) + { + if (err == 3) + { + /* + We were saving DATETIME into a DATE column, the conversion went ok + but a non-zero time part was cut off. + + In MySQL's SQL dialect, DATE and DATETIME are compared as datetime + values. Index over a DATE column uses DATE comparison. Changing + from one comparison to the other is possible: + + datetime(date_col)< '2007-12-10 12:34:55' -> date_col<='2007-12-10' + datetime(date_col)<='2007-12-10 12:34:55' -> date_col<='2007-12-10' + + datetime(date_col)> '2007-12-10 12:34:55' -> date_col>='2007-12-10' + datetime(date_col)>='2007-12-10 12:34:55' -> date_col>='2007-12-10' + + but we'll need to convert '>' to '>=' and '<' to '<='. This will + be done together with other types at the end of this function + (grep for stored_field_cmp_to_item) + */ + if (op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL) + DBUG_RETURN(new (prm->mem_root) SEL_ARG_IMPOSSIBLE(this)); + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); + } + DBUG_RETURN(stored_field_make_mm_leaf_truncated(prm, op, value)); + } + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); +} + + +SEL_ARG *Field_str::get_mm_leaf(RANGE_OPT_PARAM *prm, KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, Item *value) +{ + DBUG_ENTER("Field_str::get_mm_leaf"); + if (!can_optimize_scalar_range(prm, key_part, cond, op, value)) + DBUG_RETURN(0); + int err= value->save_in_field_no_warnings(this, 1); + if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0) + DBUG_RETURN(&null_element); + if (err > 0) + { + if (op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL) + DBUG_RETURN(new (prm->mem_root) SEL_ARG_IMPOSSIBLE(this)); + DBUG_RETURN(NULL); /* Cannot infer anything */ + } + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); +} + + +SEL_ARG *Field::get_mm_leaf_int(RANGE_OPT_PARAM *prm, KEY_PART *key_part, + const Item_bool_func *cond, + scalar_comparison_op op, Item *value, + bool unsigned_field) +{ + DBUG_ENTER("Field::get_mm_leaf_int"); + if (!can_optimize_scalar_range(prm, key_part, cond, op, value)) + DBUG_RETURN(0); + int err= value->save_in_field_no_warnings(this, 1); + if ((op != SCALAR_CMP_EQUAL && is_real_null()) || err < 0) + DBUG_RETURN(&null_element); + if (err > 0) + { + if (value->result_type() != INT_RESULT) + DBUG_RETURN(stored_field_make_mm_leaf_truncated(prm, op, value)); + else + DBUG_RETURN(stored_field_make_mm_leaf_bounded_int(prm, key_part, + op, value, + unsigned_field)); + } + if (value->result_type() != INT_RESULT) + DBUG_RETURN(stored_field_make_mm_leaf(prm, key_part, op, value)); + DBUG_RETURN(stored_field_make_mm_leaf_exact(prm, key_part, op, value)); +} + + +/* + This method is called when: + - value->save_in_field_no_warnings() returned err > 0 + - and both field and "value" are of integer data types + If an integer got bounded (e.g. to within 0..255 / -128..127) + for < or >, set flags as for <= or >= (no NEAR_MAX / NEAR_MIN) +*/ + +SEL_ARG *Field::stored_field_make_mm_leaf_bounded_int(RANGE_OPT_PARAM *param, + KEY_PART *key_part, + scalar_comparison_op op, + Item *value, + bool unsigned_field) +{ + DBUG_ENTER("Field::stored_field_make_mm_leaf_bounded_int"); + if (op == SCALAR_CMP_EQ || op == SCALAR_CMP_EQUAL) // e.g. tinyint = 200 + DBUG_RETURN(new (param->mem_root) SEL_ARG_IMPOSSIBLE(this)); + longlong item_val= value->val_int(); + + if (op == SCALAR_CMP_LT && item_val > 0) + op= SCALAR_CMP_LE; // e.g. rewrite (tinyint < 200) to (tinyint <= 127) + else if (op == SCALAR_CMP_GT && !unsigned_field && + !value->unsigned_flag && item_val < 0) + op= SCALAR_CMP_GE; // e.g. rewrite (tinyint > -200) to (tinyint >= -128) + + /* + Check if we are comparing an UNSIGNED integer with a negative constant. + In this case we know that: + (a) (unsigned_int [< | <=] negative_constant) == FALSE + (b) (unsigned_int [> | >=] negative_constant) == TRUE + In case (a) the condition is false for all values, and in case (b) it + is true for all values, so we can avoid unnecessary retrieval and condition + testing, and we also get correct comparison of unsinged integers with + negative integers (which otherwise fails because at query execution time + negative integers are cast to unsigned if compared with unsigned). + */ + if (unsigned_field && !value->unsigned_flag && item_val < 0) + { + if (op == SCALAR_CMP_LT || op == SCALAR_CMP_LE) // e.g. uint < -1 + DBUG_RETURN(new (param->mem_root) SEL_ARG_IMPOSSIBLE(this)); + if (op == SCALAR_CMP_GT || op == SCALAR_CMP_GE) // e.g. uint > -1 + DBUG_RETURN(0); + } + DBUG_RETURN(stored_field_make_mm_leaf_exact(param, key_part, op, value)); +} + + +SEL_ARG *Field::stored_field_make_mm_leaf(RANGE_OPT_PARAM *param, + KEY_PART *key_part, + scalar_comparison_op op, + Item *value) +{ + DBUG_ENTER("Field::stored_field_make_mm_leaf"); + THD *thd= param->thd; + MEM_ROOT *mem_root= param->mem_root; + uchar *str; + if (!(str= make_key_image(param->mem_root, key_part))) + DBUG_RETURN(0); + + switch (op) { + case SCALAR_CMP_LE: + DBUG_RETURN(new (mem_root) SEL_ARG_LE(str, this)); + case SCALAR_CMP_LT: + DBUG_RETURN(new (mem_root) SEL_ARG_LT(thd, str, this, value)); + case SCALAR_CMP_GT: + DBUG_RETURN(new (mem_root) SEL_ARG_GT(thd, str, key_part, this, value)); + case SCALAR_CMP_GE: + DBUG_RETURN(new (mem_root) SEL_ARG_GE(thd, str, key_part, this, value)); + case SCALAR_CMP_EQ: + case SCALAR_CMP_EQUAL: + DBUG_RETURN(new (mem_root) SEL_ARG(this, str, str)); + break; + } + DBUG_ASSERT(0); + DBUG_RETURN(NULL); +} + + +SEL_ARG *Field::stored_field_make_mm_leaf_exact(RANGE_OPT_PARAM *param, + KEY_PART *key_part, + scalar_comparison_op op, + Item *value) +{ + DBUG_ENTER("Field::stored_field_make_mm_leaf_exact"); + uchar *str; + if (!(str= make_key_image(param->mem_root, key_part))) + DBUG_RETURN(0); + + switch (op) { + case SCALAR_CMP_LE: + DBUG_RETURN(new (param->mem_root) SEL_ARG_LE(str, this)); + case SCALAR_CMP_LT: + DBUG_RETURN(new (param->mem_root) SEL_ARG_LT(str, this)); + case SCALAR_CMP_GT: + DBUG_RETURN(new (param->mem_root) SEL_ARG_GT(str, key_part, this)); + case SCALAR_CMP_GE: + DBUG_RETURN(new (param->mem_root) SEL_ARG_GE(str, this)); + case SCALAR_CMP_EQ: + case SCALAR_CMP_EQUAL: + DBUG_RETURN(new (param->mem_root) SEL_ARG(this, str, str)); + break; + } + DBUG_ASSERT(0); + DBUG_RETURN(NULL); +} + + +/****************************************************************************** +** Tree manipulation functions +** If tree is 0 it means that the condition can't be tested. It refers +** to a non existent table or to a field in current table with isn't a key. +** The different tree flags: +** IMPOSSIBLE: Condition is never TRUE +** ALWAYS: Condition is always TRUE +** MAYBE: Condition may exists when tables are read +** MAYBE_KEY: Condition refers to a key that may be used in join loop +** KEY_RANGE: Condition uses a key +******************************************************************************/ + +/* + Update weights for SEL_ARG graph that is connected only via next_key_part + (and not left/right) links +*/ +static uint update_weight_for_single_arg(SEL_ARG *arg) +{ + if (arg->next_key_part) + return (arg->weight= 1 + update_weight_for_single_arg(arg->next_key_part)); + else + return (arg->weight= 1); +} + + +/* + Add a new key test to a key when scanning through all keys + This will never be called for same key parts. +*/ + +static SEL_ARG * +sel_add(SEL_ARG *key1,SEL_ARG *key2) +{ + SEL_ARG *root,**key_link; + + if (!key1) + return key2; + if (!key2) + return key1; + + key_link= &root; + while (key1 && key2) + { + if (key1->part < key2->part) + { + *key_link= key1; + key_link= &key1->next_key_part; + key1=key1->next_key_part; + } + else + { + *key_link= key2; + key_link= &key2->next_key_part; + key2=key2->next_key_part; + } + } + *key_link=key1 ? key1 : key2; + + update_weight_for_single_arg(root); + return root; +} + + +/* + Build a range tree for the conjunction of the range parts of two trees + + SYNOPSIS + and_range_trees() + param Context info for the operation + tree1 SEL_TREE for the first conjunct + tree2 SEL_TREE for the second conjunct + result SEL_TREE for the result + + DESCRIPTION + This function takes range parts of two trees tree1 and tree2 and builds + a range tree for the conjunction of the formulas that these two range parts + represent. + More exactly: + if the range part of tree1 represents the normalized formula + R1_1 AND ... AND R1_k, + and the range part of tree2 represents the normalized formula + R2_1 AND ... AND R2_k, + then the range part of the result represents the formula: + RT = R_1 AND ... AND R_k, where R_i=(R1_i AND R2_i) for each i from [1..k] + + The function assumes that tree1 is never equal to tree2. At the same + time the tree result can be the same as tree1 (but never as tree2). + If result==tree1 then rt replaces the range part of tree1 leaving + imerges as they are. + if result!=tree1 than it is assumed that the SEL_ARG trees in tree1 and + tree2 should be preserved. Otherwise they can be destroyed. + + RETURN + 1 if the type the result tree is SEL_TREE::IMPOSSIBLE + 0 otherwise +*/ + +static +int and_range_trees(RANGE_OPT_PARAM *param, SEL_TREE *tree1, SEL_TREE *tree2, + SEL_TREE *result) +{ + DBUG_ENTER("and_ranges"); + key_map result_keys; + result_keys.clear_all(); + key_map anded_keys= tree1->keys_map; + anded_keys.merge(tree2->keys_map); + int key_no; + key_map::Iterator it(anded_keys); + while ((key_no= it++) != key_map::Iterator::BITMAP_END) + { + uint flag=0; + SEL_ARG *key1= tree1->keys[key_no]; + SEL_ARG *key2= tree2->keys[key_no]; + if (key1 && !key1->simple_key()) + flag|= CLONE_KEY1_MAYBE; + if (key2 && !key2->simple_key()) + flag|=CLONE_KEY2_MAYBE; + if (result != tree1) + { + if (key1) + key1->incr_refs(); + if (key2) + key2->incr_refs(); + } + SEL_ARG *key; + if ((result->keys[key_no]= key= key_and_with_limit(param, key_no, + key1, key2, flag))) + { + if (key && key->type == SEL_ARG::IMPOSSIBLE) + { + result->type= SEL_TREE::IMPOSSIBLE; + if (param->using_real_indexes) + { + param->table->with_impossible_ranges.set_bit(param-> + real_keynr[key_no]); + } + DBUG_RETURN(1); + } + result_keys.set_bit(key_no); +#ifdef EXTRA_DEBUG + if (param->alloced_sel_args < SEL_ARG::MAX_SEL_ARGS) + key->test_use_count(key); +#endif + } + } + result->keys_map= result_keys; + DBUG_RETURN(0); +} + + +/* + Build a SEL_TREE for a conjunction out of such trees for the conjuncts + + SYNOPSIS + tree_and() + param Context info for the operation + tree1 SEL_TREE for the first conjunct + tree2 SEL_TREE for the second conjunct + + DESCRIPTION + This function builds a tree for the formula (A AND B) out of the trees + tree1 and tree2 that has been built for the formulas A and B respectively. + + In a general case + tree1 represents the formula RT1 AND MT1, + where RT1 = R1_1 AND ... AND R1_k1, MT1=M1_1 AND ... AND M1_l1; + tree2 represents the formula RT2 AND MT2 + where RT2 = R2_1 AND ... AND R2_k2, MT2=M2_1 AND ... AND M2_l2. + + The result tree will represent the formula of the the following structure: + RT AND RT1MT2 AND RT2MT1, such that + rt is a tree obtained by range intersection of trees tree1 and tree2, + RT1MT2 = RT1M2_1 AND ... AND RT1M2_l2, + RT2MT1 = RT2M1_1 AND ... AND RT2M1_l1, + where rt1m2_i (i=1,...,l2) is the result of the pushdown operation + of range tree rt1 into imerge m2_i, while rt2m1_j (j=1,...,l1) is the + result of the pushdown operation of range tree rt2 into imerge m1_j. + + RT1MT2/RT2MT is empty if MT2/MT1 is empty. + + The range intersection of two range trees is produced by the function + and_range_trees. The pushdown of a range tree to a imerge is performed + by the function imerge_list_and_tree. This function may produce imerges + containing only one range tree. Such trees are intersected with rt and + the result of intersection is returned as the range part of the result + tree, while the corresponding imerges are removed altogether from its + imerge part. + + NOTE + The pushdown operation of range trees into imerges is needed to be able + to construct valid imerges for the condition like this: + key1_p1=c1 AND (key1_p2 BETWEEN c21 AND c22 OR key2 < c2) + + NOTE + Currently we do not support intersection between indexes and index merges. + When this will be supported the list of imerges for the result tree + should include also imerges from M1 and M2. That's why an extra parameter + is added to the function imerge_list_and_tree. If we call the function + with the last parameter equal to FALSE then MT1 and MT2 will be preserved + in the imerge list of the result tree. This can lead to the exponential + growth of the imerge list though. + Currently the last parameter of imerge_list_and_tree calls is always + TRUE. + + RETURN + The result tree, if a success + 0 - otherwise. +*/ + +static +SEL_TREE *tree_and(RANGE_OPT_PARAM *param, SEL_TREE *tree1, SEL_TREE *tree2) +{ + DBUG_ENTER("tree_and"); + if (!tree1) + DBUG_RETURN(tree2); + if (!tree2) + DBUG_RETURN(tree1); + if (tree1->type == SEL_TREE::IMPOSSIBLE || tree2->type == SEL_TREE::ALWAYS) + DBUG_RETURN(tree1); + if (tree2->type == SEL_TREE::IMPOSSIBLE || tree1->type == SEL_TREE::ALWAYS) + DBUG_RETURN(tree2); + if (tree1->type == SEL_TREE::MAYBE) + { + if (tree2->type == SEL_TREE::KEY) + tree2->type=SEL_TREE::KEY_SMALLER; + DBUG_RETURN(tree2); + } + if (tree2->type == SEL_TREE::MAYBE) + { + tree1->type=SEL_TREE::KEY_SMALLER; + DBUG_RETURN(tree1); + } + + if (!tree1->merges.is_empty()) + imerge_list_and_tree(param, &tree1->merges, tree2, TRUE); + if (!tree2->merges.is_empty()) + imerge_list_and_tree(param, &tree2->merges, tree1, TRUE); + if (and_range_trees(param, tree1, tree2, tree1)) + DBUG_RETURN(tree1); + imerge_list_and_list(&tree1->merges, &tree2->merges); + eliminate_single_tree_imerges(param, tree1); + DBUG_RETURN(tree1); +} + + +/* + Eliminate single tree imerges in a SEL_TREE objects + + SYNOPSIS + eliminate_single_tree_imerges() + param Context info for the function + tree SEL_TREE where single tree imerges are to be eliminated + + DESCRIPTION + For each imerge in 'tree' that contains only one disjunct tree, i.e. + for any imerge of the form m=rt, the function performs and operation + the range part of tree, replaces rt the with the result of anding and + removes imerge m from the the merge part of 'tree'. + + RETURN VALUE + none +*/ + +static +void eliminate_single_tree_imerges(RANGE_OPT_PARAM *param, SEL_TREE *tree) +{ + SEL_IMERGE *imerge; + List<SEL_IMERGE> merges= tree->merges; + List_iterator<SEL_IMERGE> it(merges); + tree->merges.empty(); + while ((imerge= it++)) + { + if (imerge->trees+1 == imerge->trees_next) + { + tree= tree_and(param, tree, *imerge->trees); + it.remove(); + } + } + tree->merges= merges; +} + + +/* + For two trees check that there are indexes with ranges in both of them + + SYNOPSIS + sel_trees_have_common_keys() + tree1 SEL_TREE for the first tree + tree2 SEL_TREE for the second tree + common_keys OUT bitmap of all indexes with ranges in both trees + + DESCRIPTION + For two trees tree1 and tree1 the function checks if there are indexes + in their range parts such that SEL_ARG trees are defined for them in the + range parts of both trees. The function returns the bitmap of such + indexes in the parameter common_keys. + + RETURN + TRUE if there are such indexes (common_keys is nor empty) + FALSE otherwise +*/ + +static +bool sel_trees_have_common_keys(SEL_TREE *tree1, SEL_TREE *tree2, + key_map *common_keys) +{ + *common_keys= tree1->keys_map; + common_keys->intersect(tree2->keys_map); + return !common_keys->is_clear_all(); +} + + +/* + Check whether range parts of two trees can be ored for some indexes + + SYNOPSIS + sel_trees_can_be_ored() + param Context info for the function + tree1 SEL_TREE for the first tree + tree2 SEL_TREE for the second tree + common_keys IN/OUT IN: bitmap of all indexes with SEL_ARG in both trees + OUT: bitmap of all indexes that can be ored + + DESCRIPTION + For two trees tree1 and tree2 and the bitmap common_keys containing + bits for indexes that have SEL_ARG trees in range parts of both trees + the function checks if there are indexes for which SEL_ARG trees can + be ored. Two SEL_ARG trees for the same index can be ored if the most + major components of the index used in these trees coincide. If the + SEL_ARG trees for an index cannot be ored the function clears the bit + for this index in the bitmap common_keys. + + The function does not verify that indexes marked in common_keys really + have SEL_ARG trees in both tree1 and tree2. It assumes that this is true. + + NOTE + The function sel_trees_can_be_ored is usually used in pair with the + function sel_trees_have_common_keys. + + RETURN + TRUE if there are indexes for which SEL_ARG trees can be ored + FALSE otherwise +*/ + +static +bool sel_trees_can_be_ored(RANGE_OPT_PARAM* param, + SEL_TREE *tree1, SEL_TREE *tree2, + key_map *common_keys) +{ + DBUG_ENTER("sel_trees_can_be_ored"); + if (!sel_trees_have_common_keys(tree1, tree2, common_keys)) + DBUG_RETURN(FALSE); + int key_no; + key_map::Iterator it(*common_keys); + while ((key_no= it++) != key_map::Iterator::BITMAP_END) + { + DBUG_ASSERT(tree1->keys[key_no] && tree2->keys[key_no]); + /* Trees have a common key, check if they refer to the same key part */ + if (tree1->keys[key_no]->part != tree2->keys[key_no]->part) + common_keys->clear_bit(key_no); + } + DBUG_RETURN(!common_keys->is_clear_all()); +} + +/* + Check whether the key parts inf_init..inf_end-1 of one index can compose + an infix for the key parts key_init..key_end-1 of another index +*/ + +static +bool is_key_infix(KEY_PART *key_init, KEY_PART *key_end, + KEY_PART *inf_init, KEY_PART *inf_end) +{ + KEY_PART *key_part, *inf_part; + for (key_part= key_init; key_part < key_end; key_part++) + { + if (key_part->field->eq(inf_init->field)) + break; + } + if (key_part == key_end) + return false; + for (key_part++, inf_part= inf_init + 1; + key_part < key_end && inf_part < inf_end; + key_part++, inf_part++) + { + if (!key_part->field->eq(inf_part->field)) + return false; + } + return inf_part == inf_end; +} + + +/* + Check whether range parts of two trees must be ored for some indexes + + SYNOPSIS + sel_trees_must_be_ored() + param Context info for the function + tree1 SEL_TREE for the first tree + tree2 SEL_TREE for the second tree + ordable_keys bitmap of SEL_ARG trees that can be ored + + DESCRIPTION + For two trees tree1 and tree2 the function checks whether they must be + ored. The function assumes that the bitmap ordable_keys contains bits for + those corresponding pairs of SEL_ARG trees from tree1 and tree2 that can + be ored. + We believe that tree1 and tree2 must be ored if any pair of SEL_ARG trees + r1 and r2, such that r1 is from tree1 and r2 is from tree2 and both + of them are marked in ordable_keys, can be merged. + + NOTE + The function sel_trees_must_be_ored as a rule is used in pair with the + function sel_trees_can_be_ored. + + RETURN + TRUE if there are indexes for which SEL_ARG trees must be ored + FALSE otherwise +*/ + +static +bool sel_trees_must_be_ored(RANGE_OPT_PARAM* param, + SEL_TREE *tree1, SEL_TREE *tree2, + key_map oredable_keys) +{ + key_map tmp; + DBUG_ENTER("sel_trees_must_be_ored"); + + tmp= tree1->keys_map; + tmp.merge(tree2->keys_map); + tmp.subtract(oredable_keys); + if (!tmp.is_clear_all()) + DBUG_RETURN(FALSE); + + int idx1, idx2; + key_map::Iterator it1(oredable_keys); + while ((idx1= it1++) != key_map::Iterator::BITMAP_END) + { + KEY_PART *key1_init= param->key[idx1]+tree1->keys[idx1]->part; + KEY_PART *key1_end= param->key[idx1]+tree1->keys[idx1]->max_part_no; + key_map::Iterator it2(oredable_keys); + while ((idx2= it2++) != key_map::Iterator::BITMAP_END) + { + if (idx2 <= idx1) + continue; + + KEY_PART *key2_init= param->key[idx2]+tree2->keys[idx2]->part; + KEY_PART *key2_end= param->key[idx2]+tree2->keys[idx2]->max_part_no; + if (!is_key_infix(key1_init, key1_end, key2_init, key2_end) && + !is_key_infix(key2_init, key2_end, key1_init, key1_end)) + DBUG_RETURN(FALSE); + } + } + + DBUG_RETURN(TRUE); +} + + +/* + Remove the trees that are not suitable for record retrieval + + SYNOPSIS + remove_nonrange_trees() + param Context info for the function + tree Tree to be processed, tree->type is KEY or KEY_SMALLER + + DESCRIPTION + This function walks through tree->keys[] and removes the SEL_ARG* trees + that are not "maybe" trees (*) and cannot be used to construct quick range + selects. + (*) - have type MAYBE or MAYBE_KEY. Perhaps we should remove trees of + these types here as well. + + A SEL_ARG* tree cannot be used to construct quick select if it has + tree->part != 0. (e.g. it could represent "keypart2 < const"). + + Normally we allow construction of SEL_TREE objects that have SEL_ARG + trees that do not allow quick range select construction. + For example: + for " keypart1=1 AND keypart2=2 " the execution will proceed as follows: + tree1= SEL_TREE { SEL_ARG{keypart1=1} } + tree2= SEL_TREE { SEL_ARG{keypart2=2} } -- can't make quick range select + from this + call tree_and(tree1, tree2) -- this joins SEL_ARGs into a usable SEL_ARG + tree. + + Another example: + tree3= SEL_TREE { SEL_ARG{key1part1 = 1} } + tree4= SEL_TREE { SEL_ARG{key2part2 = 2} } -- can't make quick range select + from this + call tree_or(tree3, tree4) -- creates a SEL_MERGE ot of which no index + merge can be constructed, but it is potentially useful, as anding it with + tree5= SEL_TREE { SEL_ARG{key2part1 = 3} } creates an index merge that + represents the formula + key1part1=1 AND key2part1=3 OR key2part1=3 AND key2part2=2 + for which an index merge can be built. + + Any final SEL_TREE may contain SEL_ARG trees for which no quick select + can be built. Such SEL_ARG trees should be removed from the range part + before different range scans are evaluated. Such SEL_ARG trees also should + be removed from all range trees of each index merge before different + possible index merge plans are evaluated. If after this removal one + of the range trees in the index merge becomes empty the whole index merge + must be discarded. + + RETURN + 0 Ok, some suitable trees left + 1 No tree->keys[] left. +*/ + +static bool remove_nonrange_trees(PARAM *param, SEL_TREE *tree) +{ + bool res= FALSE; + for (uint i=0; i < param->keys; i++) + { + if (tree->keys[i]) + { + if (tree->keys[i]->part) + { + tree->keys[i]= NULL; + /* Mark that records_in_range has not been called */ + param->quick_rows[param->real_keynr[i]]= HA_POS_ERROR; + tree->keys_map.clear_bit(i); + } + else + res= TRUE; + } + } + return !res; +} + + +/* + Restore nonrange trees to their previous state +*/ + +static void restore_nonrange_trees(RANGE_OPT_PARAM *param, SEL_TREE *tree, + SEL_ARG **backup_keys) +{ + for (uint i=0; i < param->keys; i++) + { + if (backup_keys[i]) + { + tree->keys[i]= backup_keys[i]; + tree->keys_map.set_bit(i); + } + } +} + +/* + Build a SEL_TREE for a disjunction out of such trees for the disjuncts + + SYNOPSIS + tree_or() + param Context info for the operation + tree1 SEL_TREE for the first disjunct + tree2 SEL_TREE for the second disjunct + + DESCRIPTION + This function builds a tree for the formula (A OR B) out of the trees + tree1 and tree2 that has been built for the formulas A and B respectively. + + In a general case + tree1 represents the formula RT1 AND MT1, + where RT1=R1_1 AND ... AND R1_k1, MT1=M1_1 AND ... AND M1_l1; + tree2 represents the formula RT2 AND MT2 + where RT2=R2_1 AND ... AND R2_k2, MT2=M2_1 and ... and M2_l2. + + The function constructs the result tree according the formula + (RT1 OR RT2) AND (MT1 OR RT1) AND (MT2 OR RT2) AND (MT1 OR MT2) + that is equivalent to the formula (RT1 AND MT1) OR (RT2 AND MT2). + + To limit the number of produced imerges the function considers + a weaker formula than the original one: + (RT1 AND M1_1) OR (RT2 AND M2_1) + that is equivalent to: + (RT1 OR RT2) (1) + AND + (M1_1 OR M2_1) (2) + AND + (M1_1 OR RT2) (3) + AND + (M2_1 OR RT1) (4) + + For the first conjunct (1) the function builds a tree with a range part + and, possibly, one imerge. For the other conjuncts (2-4)the function + produces sets of imerges. All constructed imerges are included into the + result tree. + + For the formula (1) the function produces the tree representing a formula + of the structure RT [AND M], such that: + - the range tree rt contains the result of oring SEL_ARG trees from rt1 + and rt2 + - the imerge m consists of two range trees rt1 and rt2. + The imerge m is added if it's not true that rt1 and rt2 must be ored + If rt1 and rt2 can't be ored rt is empty and only m is produced for (1). + + To produce imerges for the formula (2) the function calls the function + imerge_list_or_list passing it the merge parts of tree1 and tree2 as + parameters. + + To produce imerges for the formula (3) the function calls the function + imerge_list_or_tree passing it the imerge m1_1 and the range tree rt2 as + parameters. Similarly, to produce imerges for the formula (4) the function + calls the function imerge_list_or_tree passing it the imerge m2_1 and the + range tree rt1. + + If rt1 is empty then the trees for (1) and (4) are empty. + If rt2 is empty then the trees for (1) and (3) are empty. + If mt1 is empty then the trees for (2) and (3) are empty. + If mt2 is empty then the trees for (2) and (4) are empty. + + RETURN + The result tree for the operation if a success + 0 - otherwise +*/ + +static SEL_TREE * +tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2) +{ + DBUG_ENTER("tree_or"); + if (!tree1 || !tree2) + DBUG_RETURN(0); + if (tree1->type == SEL_TREE::IMPOSSIBLE || tree2->type == SEL_TREE::ALWAYS) + DBUG_RETURN(tree2); + if (tree2->type == SEL_TREE::IMPOSSIBLE || tree1->type == SEL_TREE::ALWAYS) + DBUG_RETURN(tree1); + if (tree1->type == SEL_TREE::MAYBE) + DBUG_RETURN(tree1); // Can't use this + if (tree2->type == SEL_TREE::MAYBE) + DBUG_RETURN(tree2); + + SEL_TREE *result= NULL; + key_map result_keys; + key_map ored_keys; + SEL_TREE *rtree[2]= {NULL,NULL}; + SEL_IMERGE *imerge[2]= {NULL, NULL}; + bool no_ranges1= tree1->without_ranges(); + bool no_ranges2= tree2->without_ranges(); + bool no_merges1= tree1->without_imerges(); + bool no_merges2= tree2->without_imerges(); + if (!no_ranges1 && !no_merges2) + { + rtree[0]= new SEL_TREE(tree1, TRUE, param); + imerge[1]= new SEL_IMERGE(tree2->merges.head(), 0, param); + } + if (!no_ranges2 && !no_merges1) + { + rtree[1]= new SEL_TREE(tree2, TRUE, param); + imerge[0]= new SEL_IMERGE(tree1->merges.head(), 0, param); + } + bool no_imerge_from_ranges= FALSE; + + /* Build the range part of the tree for the formula (1) */ + if (sel_trees_can_be_ored(param, tree1, tree2, &ored_keys)) + { + bool must_be_ored= sel_trees_must_be_ored(param, tree1, tree2, ored_keys); + no_imerge_from_ranges= must_be_ored; + + if (no_imerge_from_ranges && no_merges1 && no_merges2) + { + /* + Reuse tree1 as the result in simple cases. This reduces memory usage + for e.g. "key IN (c1, ..., cN)" which produces a lot of ranges. + */ + result= tree1; + result->keys_map.clear_all(); + } + else + { + if (!(result= new (param->mem_root) SEL_TREE(param->mem_root, + param->keys))) + { + DBUG_RETURN(result); + } + } + + key_map::Iterator it(ored_keys); + int key_no; + while ((key_no= it++) != key_map::Iterator::BITMAP_END) + { + SEL_ARG *key1= tree1->keys[key_no]; + SEL_ARG *key2= tree2->keys[key_no]; + if (!must_be_ored) + { + key1->incr_refs(); + key2->incr_refs(); + } + if ((result->keys[key_no]= key_or_with_limit(param, key_no, key1, key2))) + result->keys_map.set_bit(key_no); + } + result->type= tree1->type; + } + else + { + if (!result && !(result= new (param->mem_root) SEL_TREE(param->mem_root, + param->keys))) + DBUG_RETURN(result); + } + + if (no_imerge_from_ranges && no_merges1 && no_merges2) + { + if (result->keys_map.is_clear_all()) + result->type= SEL_TREE::ALWAYS; + DBUG_RETURN(result); + } + + SEL_IMERGE *imerge_from_ranges; + if (!(imerge_from_ranges= new SEL_IMERGE())) + result= NULL; + else if (!no_ranges1 && !no_ranges2 && !no_imerge_from_ranges) + { + /* Build the imerge part of the tree for the formula (1) */ + SEL_TREE *rt1= tree1; + SEL_TREE *rt2= tree2; + if (no_merges1) + rt1= new SEL_TREE(tree1, TRUE, param); + if (no_merges2) + rt2= new SEL_TREE(tree2, TRUE, param); + if (!rt1 || !rt2 || + result->merges.push_back(imerge_from_ranges) || + imerge_from_ranges->or_sel_tree(param, rt1) || + imerge_from_ranges->or_sel_tree(param, rt2)) + result= NULL; + } + if (!result) + DBUG_RETURN(result); + + result->type= tree1->type; + + if (!no_merges1 && !no_merges2 && + !imerge_list_or_list(param, &tree1->merges, &tree2->merges)) + { + /* Build the imerges for the formula (2) */ + imerge_list_and_list(&result->merges, &tree1->merges); + } + + /* Build the imerges for the formulas (3) and (4) */ + for (uint i=0; i < 2; i++) + { + List<SEL_IMERGE> merges; + SEL_TREE *rt= rtree[i]; + SEL_IMERGE *im= imerge[1-i]; + + if (rt && im && !merges.push_back(im) && + !imerge_list_or_tree(param, &merges, rt)) + imerge_list_and_list(&result->merges, &merges); + } + + DBUG_RETURN(result); +} + + +/* And key trees where key1->part < key2 -> part */ + +static SEL_ARG * +and_all_keys(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2, + uint clone_flag) +{ + SEL_ARG *next; + ulong use_count=key1->use_count; + + if (sel_arg_and_weight_heuristic(param, key1, key2)) + return key1; + + if (key1->elements != 1) + { + key2->use_count+=key1->elements-1; //psergey: why we don't count that key1 has n-k-p? + key2->increment_use_count((int) key1->elements-1); + } + if (key1->type == SEL_ARG::MAYBE_KEY) + { + if (key2->type == SEL_ARG::KEY_RANGE) + return key2; + key1->right= key1->left= &null_element; + key1->next= key1->prev= 0; + } + + for (next=key1->first(); next ; next=next->next) + { + if (next->next_key_part) + { + SEL_ARG *tmp= key_and(param, next->next_key_part, key2, clone_flag); + if (tmp && tmp->type == SEL_ARG::IMPOSSIBLE) + { + key1=key1->tree_delete(next); + continue; + } + next->next_key_part=tmp; + if (use_count) + next->increment_use_count(use_count); + if (param->alloced_sel_args > SEL_ARG::MAX_SEL_ARGS) + break; + } + else + next->next_key_part=key2; + } + if (!key1) + return &null_element; // Impossible ranges + key1->use_count++; + + /* Re-compute the result tree's weight. */ + key1->update_weight_locally(); + + key1->max_part_no= MY_MAX(key2->max_part_no, key2->part+1); + return key1; +} + + +/* + Produce a SEL_ARG graph that represents "key1 AND key2" + + SYNOPSIS + key_and() + param Range analysis context (needed to track if we have allocated + too many SEL_ARGs) + key1 First argument, root of its RB-tree + key2 Second argument, root of its RB-tree + + RETURN + RB-tree root of the resulting SEL_ARG graph. + NULL if the result of AND operation is an empty interval {0}. +*/ + +static SEL_ARG * +key_and(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2, uint clone_flag) +{ + if (!key1) + return key2; + if (!key2) + return key1; + if (key1->part != key2->part) + { + if (key1->part > key2->part) + { + swap_variables(SEL_ARG *, key1, key2); + clone_flag=swap_clone_flag(clone_flag); + } + // key1->part < key2->part + + if (sel_arg_and_weight_heuristic(param, key1, key2)) + return key1; + + key1->use_count--; + if (key1->use_count > 0) + if (!(key1= key1->clone_tree(param))) + return 0; // OOM + return and_all_keys(param, key1, key2, clone_flag); + } + + if (((clone_flag & CLONE_KEY2_MAYBE) && + !(clone_flag & CLONE_KEY1_MAYBE) && + key2->type != SEL_ARG::MAYBE_KEY) || + key1->type == SEL_ARG::MAYBE_KEY) + { // Put simple key in key2 + swap_variables(SEL_ARG *, key1, key2); + clone_flag=swap_clone_flag(clone_flag); + } + + /* If one of the key is MAYBE_KEY then the found region may be smaller */ + if (key2->type == SEL_ARG::MAYBE_KEY) + { + if (key1->use_count > 1) + { + key1->use_count--; + if (!(key1=key1->clone_tree(param))) + return 0; // OOM + key1->use_count++; + } + if (key1->type == SEL_ARG::MAYBE_KEY) + { // Both are maybe key + key1->next_key_part=key_and(param, key1->next_key_part, + key2->next_key_part, clone_flag); + + key1->weight= 1 + (key1->next_key_part? key1->next_key_part->weight : 0); + + if (key1->next_key_part && + key1->next_key_part->type == SEL_ARG::IMPOSSIBLE) + return key1; + } + else + { + key1->maybe_smaller(); + if (key2->next_key_part) + { + key1->use_count--; // Incremented in and_all_keys + return and_all_keys(param, key1, key2->next_key_part, clone_flag); + } + key2->use_count--; // Key2 doesn't have a tree + } + return key1; + } + + if ((key1->min_flag | key2->min_flag) & GEOM_FLAG) + { + /* TODO: why not leave one of the trees? */ + key1->free_tree(); + key2->free_tree(); + return 0; // Can't optimize this + } + + key1->use_count--; + key2->use_count--; + SEL_ARG *e1=key1->first(), *e2=key2->first(), *new_tree=0; + uint max_part_no= MY_MAX(key1->max_part_no, key2->max_part_no); + + while (e1 && e2) + { + int cmp=e1->cmp_min_to_min(e2); + if (cmp < 0) + { + if (get_range(&e1,&e2,key1)) + continue; + } + else if (get_range(&e2,&e1,key2)) + continue; + SEL_ARG *next=key_and(param, e1->next_key_part, e2->next_key_part, + clone_flag); + e1->incr_refs(); + e2->incr_refs(); + if (!next || next->type != SEL_ARG::IMPOSSIBLE) + { + SEL_ARG *new_arg= e1->clone_and(param->thd, e2); + if (!new_arg) + return &null_element; // End of memory + new_arg->next_key_part=next; + if (new_arg->next_key_part) + new_arg->weight += new_arg->next_key_part->weight; + + if (!new_tree) + { + new_tree=new_arg; + } + else + new_tree=new_tree->insert(new_arg); + } + if (e1->cmp_max_to_max(e2) < 0) + e1=e1->next; // e1 can't overlapp next e2 + else + e2=e2->next; + } + key1->free_tree(); + key2->free_tree(); + if (!new_tree) + return &null_element; // Impossible range + new_tree->max_part_no= max_part_no; + return new_tree; +} + + +static bool +get_range(SEL_ARG **e1,SEL_ARG **e2,SEL_ARG *root1) +{ + (*e1)=root1->find_range(*e2); // first e1->min < e2->min + if ((*e1)->cmp_max_to_min(*e2) < 0) + { + if (!((*e1)=(*e1)->next)) + return 1; + if ((*e1)->cmp_min_to_max(*e2) > 0) + { + (*e2)=(*e2)->next; + return 1; + } + } + return 0; +} + +/* + @brief + Update the tree weight. + + @detail + Utility function to be called on a SEL_ARG tree root after doing local + modifications concerning changes at this key part. + Assumes that the weight of the graphs connected via next_key_part is + up to dayte. +*/ +void SEL_ARG::update_weight_locally() +{ + uint new_weight= 0; + const SEL_ARG *sl; + for (sl= first(); sl ; sl= sl->next) + { + new_weight++; + if (sl->next_key_part) + new_weight += sl->next_key_part->weight; + } + weight= new_weight; +} + + +#ifndef DBUG_OFF +/* + Verify SEL_TREE's weight. + + Recompute the weight and compare +*/ +uint SEL_ARG::verify_weight() +{ + uint computed_weight= 0; + SEL_ARG *first_arg= first(); + + if (first_arg) + { + for (SEL_ARG *arg= first_arg; arg; arg= arg->next) + { + computed_weight++; + if (arg->next_key_part) + computed_weight+= arg->next_key_part->verify_weight(); + } + } + else + { + // first()=NULL means this is a special kind of SEL_ARG, e.g. + // SEL_ARG with type=MAYBE_KEY + computed_weight= 1; + if (next_key_part) + computed_weight += next_key_part->verify_weight(); + } + + if (computed_weight != weight) + { + sql_print_error("SEL_ARG weight mismatch: computed %u have %u\n", + computed_weight, weight); + DBUG_ASSERT(computed_weight == weight); // Fail an assertion + } + return computed_weight; +} +#endif + +static +SEL_ARG *key_or_with_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *key1, SEL_ARG *key2) +{ +#ifndef DBUG_OFF + if (key1) + key1->verify_weight(); + if (key2) + key2->verify_weight(); +#endif + + SEL_ARG *res= key_or(param, key1, key2); + res= enforce_sel_arg_weight_limit(param, keyno, res); +#ifndef DBUG_OFF + if (res) + res->verify_weight(); +#endif + return res; +} + + +static +SEL_ARG *key_and_with_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *key1, SEL_ARG *key2, uint clone_flag) +{ +#ifndef DBUG_OFF + if (key1) + key1->verify_weight(); + if (key2) + key2->verify_weight(); +#endif + SEL_ARG *res= key_and(param, key1, key2, clone_flag); + res= enforce_sel_arg_weight_limit(param, keyno, res); +#ifndef DBUG_OFF + if (res) + res->verify_weight(); +#endif + return res; +} + + +/** + Combine two range expression under a common OR. On a logical level, the + transformation is key_or( expr1, expr2 ) => expr1 OR expr2. + + Both expressions are assumed to be in the SEL_ARG format. In a logic sense, + theformat is reminiscent of DNF, since an expression such as the following + + ( 1 < kp1 < 10 AND p1 ) OR ( 10 <= kp2 < 20 AND p2 ) + + where there is a key consisting of keyparts ( kp1, kp2, ..., kpn ) and p1 + and p2 are valid SEL_ARG expressions over keyparts kp2 ... kpn, is a valid + SEL_ARG condition. The disjuncts appear ordered by the minimum endpoint of + the first range and ranges must not overlap. It follows that they are also + ordered by maximum endpoints. Thus + + ( 1 < kp1 <= 2 AND ( kp2 = 2 OR kp2 = 3 ) ) OR kp1 = 3 + + Is a a valid SER_ARG expression for a key of at least 2 keyparts. + + For simplicity, we will assume that expr2 is a single range predicate, + i.e. on the form ( a < x < b AND ... ). It is easy to generalize to a + disjunction of several predicates by subsequently call key_or for each + disjunct. + + The algorithm iterates over each disjunct of expr1, and for each disjunct + where the first keypart's range overlaps with the first keypart's range in + expr2: + + If the predicates are equal for the rest of the keyparts, or if there are + no more, the range in expr2 has its endpoints copied in, and the SEL_ARG + node in expr2 is deallocated. If more ranges became connected in expr1, the + surplus is also dealocated. If they differ, two ranges are created. + + - The range leading up to the overlap. Empty if endpoints are equal. + + - The overlapping sub-range. May be the entire range if they are equal. + + Finally, there may be one more range if expr2's first keypart's range has a + greater maximum endpoint than the last range in expr1. + + For the overlapping sub-range, we recursively call key_or. Thus in order to + compute key_or of + + (1) ( 1 < kp1 < 10 AND 1 < kp2 < 10 ) + + (2) ( 2 < kp1 < 20 AND 4 < kp2 < 20 ) + + We create the ranges 1 < kp <= 2, 2 < kp1 < 10, 10 <= kp1 < 20. For the + first one, we simply hook on the condition for the second keypart from (1) + : 1 < kp2 < 10. For the second range 2 < kp1 < 10, key_or( 1 < kp2 < 10, 4 + < kp2 < 20 ) is called, yielding 1 < kp2 < 20. For the last range, we reuse + the range 4 < kp2 < 20 from (2) for the second keypart. The result is thus + + ( 1 < kp1 <= 2 AND 1 < kp2 < 10 ) OR + ( 2 < kp1 < 10 AND 1 < kp2 < 20 ) OR + ( 10 <= kp1 < 20 AND 4 < kp2 < 20 ) +*/ +static SEL_ARG * +key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2) +{ + if (!key1) + { + if (key2) + { + key2->use_count--; + key2->free_tree(); + } + return 0; + } + if (!key2) + { + key1->use_count--; + key1->free_tree(); + return 0; + } + key1->use_count--; + key2->use_count--; + + if (key1->part != key2->part || + (key1->min_flag | key2->min_flag) & GEOM_FLAG) + { + key1->free_tree(); + key2->free_tree(); + return 0; // Can't optimize this + } + + // If one of the key is MAYBE_KEY then the found region may be bigger + if (key1->type == SEL_ARG::MAYBE_KEY) + { + key2->free_tree(); + key1->use_count++; + return key1; + } + if (key2->type == SEL_ARG::MAYBE_KEY) + { + key1->free_tree(); + key2->use_count++; + return key2; + } + + if (key1->use_count > 0) + { + if (key2->use_count == 0 || key1->elements > key2->elements) + { + swap_variables(SEL_ARG *,key1,key2); + } + if (key1->use_count > 0 && !(key1=key1->clone_tree(param))) + return 0; // OOM + } + + // Add tree at key2 to tree at key1 + bool key2_shared=key2->use_count != 0; + key1->maybe_flag|=key2->maybe_flag; + + /* + Notation for illustrations used in the rest of this function: + + Range: [--------] + ^ ^ + start stop + + Two overlapping ranges: + [-----] [----] [--] + [---] or [---] or [-------] + + Ambiguity: *** + The range starts or stops somewhere in the "***" range. + Example: a starts before b and may end before/the same plase/after b + a: [----***] + b: [---] + + Adjacent ranges: + Ranges that meet but do not overlap. Example: a = "x < 3", b = "x >= 3" + a: ----] + b: [---- + */ + + uint max_part_no= MY_MAX(key1->max_part_no, key2->max_part_no); + + for (key2=key2->first(); key2; ) + { + /* + key1 consists of one or more ranges. tmp is the range currently + being handled. + + initialize tmp to the latest range in key1 that starts the same + place or before the range in key2 starts + + key2: [------] + key1: [---] [-----] [----] + ^ + tmp + */ + SEL_ARG *tmp=key1->find_range(key2); + + /* + Used to describe how two key values are positioned compared to + each other. Consider key_value_a.<cmp_func>(key_value_b): + + -2: key_value_a is smaller than key_value_b, and they are adjacent + -1: key_value_a is smaller than key_value_b (not adjacent) + 0: the key values are equal + 1: key_value_a is bigger than key_value_b (not adjacent) + -2: key_value_a is bigger than key_value_b, and they are adjacent + + Example: "cmp= tmp->cmp_max_to_min(key2)" + + key2: [-------- (10 <= x ...) + tmp: -----] (... x < 10) => cmp==-2 + tmp: ----] (... x <= 9) => cmp==-1 + tmp: ------] (... x = 10) => cmp== 0 + tmp: --------] (... x <= 12) => cmp== 1 + (cmp == 2 does not make sense for cmp_max_to_min()) + */ + int cmp= 0; + + if (!tmp) + { + /* + The range in key2 starts before the first range in key1. Use + the first range in key1 as tmp. + + key2: [--------] + key1: [****--] [----] [-------] + ^ + tmp + */ + tmp=key1->first(); + cmp= -1; + } + else if ((cmp= tmp->cmp_max_to_min(key2)) < 0) + { + /* + This is the case: + key2: [-------] + tmp: [----**] + */ + SEL_ARG *next=tmp->next; + if (cmp == -2 && eq_tree(tmp->next_key_part,key2->next_key_part)) + { + /* + Adjacent (cmp==-2) and equal next_key_parts => ranges can be merged + + This is the case: + key2: [-------] + tmp: [----] + + Result: + key2: [-------------] => inserted into key1 below + tmp: => deleted + */ + SEL_ARG *key2_next=key2->next; + if (key2_shared) + { + if (!(key2=new SEL_ARG(*key2))) + return 0; // out of memory + key2->increment_use_count(key1->use_count+1); + key2->next=key2_next; // New copy of key2 + } + + key2->copy_min(tmp); + if (!(key1=key1->tree_delete(tmp))) + { // Only one key in tree + key1=key2; + key1->make_root(); + key2=key2_next; + break; + } + } + if (!(tmp=next)) // Move to next range in key1. Now tmp.min > key2.min + break; // No more ranges in key1. Copy rest of key2 + } + + if (cmp < 0) + { + /* + This is the case: + key2: [--***] + tmp: [----] + */ + int tmp_cmp; + if ((tmp_cmp=tmp->cmp_min_to_max(key2)) > 0) + { + /* + This is the case: + key2: [------**] + tmp: [----] + */ + if (tmp_cmp == 2 && eq_tree(tmp->next_key_part,key2->next_key_part)) + { + /* + Adjacent ranges with equal next_key_part. Merge like this: + + This is the case: + key2: [------] + tmp: [-----] + + Result: + key2: [------] + tmp: [-------------] + + Then move on to next key2 range. + */ + tmp->copy_min_to_min(key2); + key1->merge_flags(key2); + if (tmp->min_flag & NO_MIN_RANGE && + tmp->max_flag & NO_MAX_RANGE) + { + if (key1->maybe_flag) + return new SEL_ARG(SEL_ARG::MAYBE_KEY); + return 0; + } + key2->increment_use_count(-1); // Free not used tree + key2=key2->next; + continue; + } + else + { + /* + key2 not adjacent to tmp or has different next_key_part. + Insert into key1 and move to next range in key2 + + This is the case: + key2: [------**] + tmp: [----] + + Result: + key1_ [------**][----] + ^ ^ + insert tmp + */ + SEL_ARG *next=key2->next; + if (key2_shared) + { + SEL_ARG *cpy= new SEL_ARG(*key2); // Must make copy + if (!cpy) + return 0; // OOM + key1=key1->insert(cpy); + key2->increment_use_count(key1->use_count+1); + } + else + key1=key1->insert(key2); // Will destroy key2_root + key2=next; + continue; + } + } + } + + /* + The ranges in tmp and key2 are overlapping: + + key2: [----------] + tmp: [*****-----*****] + + Corollary: tmp.min <= key2.max + */ + if (eq_tree(tmp->next_key_part,key2->next_key_part)) + { + // Merge overlapping ranges with equal next_key_part + if (tmp->is_same(key2)) + { + /* + Found exact match of key2 inside key1. + Use the relevant range in key1. + */ + tmp->merge_flags(key2); // Copy maybe flags + key2->increment_use_count(-1); // Free not used tree + } + else + { + SEL_ARG *last= tmp; + SEL_ARG *first= tmp; + + /* + Find the last range in key1 that overlaps key2 and + where all ranges first...last have the same next_key_part as + key2. + + key2: [****----------------------*******] + key1: [--] [----] [---] [-----] [xxxx] + ^ ^ ^ + first last different next_key_part + + Since key2 covers them, the ranges between first and last + are merged into one range by deleting first...last-1 from + the key1 tree. In the figure, this applies to first and the + two consecutive ranges. The range of last is then extended: + * last.min: Set to MY_MIN(key2.min, first.min) + * last.max: If there is a last->next that overlaps key2 (i.e., + last->next has a different next_key_part): + Set adjacent to last->next.min + Otherwise: Set to MY_MAX(key2.max, last.max) + + Result: + key2: [****----------------------*******] + [--] [----] [---] => deleted from key1 + key1: [**------------------------***][xxxx] + ^ ^ + tmp=last different next_key_part + */ + while (last->next && last->next->cmp_min_to_max(key2) <= 0 && + eq_tree(last->next->next_key_part,key2->next_key_part)) + { + /* + last->next is covered by key2 and has same next_key_part. + last can be deleted + */ + SEL_ARG *save=last; + last=last->next; + key1=key1->tree_delete(save); + } + // Redirect tmp to last which will cover the entire range + tmp= last; + + /* + We need the minimum endpoint of first so we can compare it + with the minimum endpoint of the enclosing key2 range. + */ + last->copy_min(first); + bool full_range= last->copy_min(key2); + if (!full_range) + { + if (last->next && key2->cmp_max_to_min(last->next) >= 0) + { + /* + This is the case: + key2: [-------------] + key1: [***------] [xxxx] + ^ ^ + last different next_key_part + + Extend range of last up to last->next: + key2: [-------------] + key1: [***--------][xxxx] + */ + last->copy_min_to_max(last->next); + } + else + /* + This is the case: + key2: [--------*****] + key1: [***---------] [xxxx] + ^ ^ + last different next_key_part + + Extend range of last up to MY_MAX(last.max, key2.max): + key2: [--------*****] + key1: [***----------**] [xxxx] + */ + full_range= last->copy_max(key2); + } + if (full_range) + { // Full range + key1->free_tree(); + for (; key2 ; key2=key2->next) + key2->increment_use_count(-1); // Free not used tree + if (key1->maybe_flag) + return new SEL_ARG(SEL_ARG::MAYBE_KEY); + return 0; + } + } + } + + if (cmp >= 0 && tmp->cmp_min_to_min(key2) < 0) + { + /* + This is the case ("cmp>=0" means that tmp.max >= key2.min): + key2: [----] + tmp: [------------*****] + */ + + if (!tmp->next_key_part) + { + SEL_ARG *key2_next= key2->next; + if (key2_shared) + { + SEL_ARG *key2_cpy= new SEL_ARG(*key2); + if (!key2_cpy) + return 0; + key2= key2_cpy; + } + /* + tmp->next_key_part is empty: cut the range that is covered + by tmp from key2. + Reason: (key2->next_key_part OR tmp->next_key_part) will be + empty and therefore equal to tmp->next_key_part. Thus, this + part of the key2 range is completely covered by tmp. + */ + if (tmp->cmp_max_to_max(key2) >= 0) + { + /* + tmp covers the entire range in key2. + key2: [----] + tmp: [-----------------] + + Move on to next range in key2 + */ + key2->increment_use_count(-1); // Free not used tree + key2=key2_next; + continue; + } + else + { + /* + This is the case: + key2: [-------] + tmp: [---------] + + Result: + key2: [---] + tmp: [---------] + */ + key2->copy_max_to_min(tmp); + continue; + } + } + + /* + The ranges are overlapping but have not been merged because + next_key_part of tmp and key2 differ. + key2: [----] + tmp: [------------*****] + + Split tmp in two where key2 starts: + key2: [----] + key1: [--------][--*****] + ^ ^ + insert tmp + */ + SEL_ARG *new_arg=tmp->clone_first(key2); + if (!new_arg) + return 0; // OOM + if ((new_arg->next_key_part= tmp->next_key_part)) + new_arg->increment_use_count(key1->use_count+1); + tmp->copy_min_to_min(key2); + key1=key1->insert(new_arg); + } // tmp.min >= key2.min due to this if() + + /* + Now key2.min <= tmp.min <= key2.max: + key2: [---------] + tmp: [****---*****] + */ + SEL_ARG key2_cpy(*key2); // Get copy we can modify + for (;;) + { + if (tmp->cmp_min_to_min(&key2_cpy) > 0) + { + /* + This is the case: + key2_cpy: [------------] + key1: [-*****] + ^ + tmp + + Result: + key2_cpy: [---] + key1: [-------][-*****] + ^ ^ + insert tmp + */ + SEL_ARG *new_arg=key2_cpy.clone_first(tmp); + if (!new_arg) + return 0; // OOM + if ((new_arg->next_key_part=key2_cpy.next_key_part)) + new_arg->increment_use_count(key1->use_count+1); + key1=key1->insert(new_arg); + key2_cpy.copy_min_to_min(tmp); + } + // Now key2_cpy.min == tmp.min + + if ((cmp= tmp->cmp_max_to_max(&key2_cpy)) <= 0) + { + /* + tmp.max <= key2_cpy.max: + key2_cpy: a) [-------] or b) [----] + tmp: [----] [----] + + Steps: + 1) Update next_key_part of tmp: OR it with key2_cpy->next_key_part. + 2) If case a: Insert range [tmp.max, key2_cpy.max] into key1 using + next_key_part of key2_cpy + + Result: + key1: a) [----][-] or b) [----] + */ + tmp->maybe_flag|= key2_cpy.maybe_flag; + key2_cpy.increment_use_count(key1->use_count+1); + + uint old_weight= tmp->next_key_part? tmp->next_key_part->weight: 0; + + tmp->next_key_part= key_or(param, tmp->next_key_part, + key2_cpy.next_key_part); + + uint new_weight= tmp->next_key_part? tmp->next_key_part->weight: 0; + key1->weight += (new_weight - old_weight); + + if (!cmp) + break; // case b: done with this key2 range + + // Make key2_cpy the range [tmp.max, key2_cpy.max] + key2_cpy.copy_max_to_min(tmp); + if (!(tmp=tmp->next)) + { + /* + No more ranges in key1. Insert key2_cpy and go to "end" + label to insert remaining ranges in key2 if any. + */ + SEL_ARG *tmp2= new SEL_ARG(key2_cpy); + if (!tmp2) + return 0; // OOM + key1=key1->insert(tmp2); + key2=key2->next; + goto end; + } + if (tmp->cmp_min_to_max(&key2_cpy) > 0) + { + /* + The next range in key1 does not overlap with key2_cpy. + Insert this range into key1 and move on to the next range + in key2. + */ + SEL_ARG *tmp2= new SEL_ARG(key2_cpy); + if (!tmp2) + return 0; // OOM + key1=key1->insert(tmp2); + break; + } + /* + key2_cpy overlaps with the next range in key1 and the case + is now "key2.min <= tmp.min <= key2.max". Go back to for(;;) + to handle this situation. + */ + continue; + } + else + { + /* + This is the case: + key2_cpy: [-------] + tmp: [------------] + + Result: + key1: [-------][---] + ^ ^ + new_arg tmp + Steps: + 0) If tmp->next_key_part is empty: do nothing. Reason: + (key2_cpy->next_key_part OR tmp->next_key_part) will be + empty and therefore equal to tmp->next_key_part. Thus, + the range in key2_cpy is completely covered by tmp + 1) Make new_arg with range [tmp.min, key2_cpy.max]. + new_arg->next_key_part is OR between next_key_part + of tmp and key2_cpy + 2) Make tmp the range [key2.max, tmp.max] + 3) Insert new_arg into key1 + */ + if (!tmp->next_key_part) // Step 0 + { + key2_cpy.increment_use_count(-1); // Free not used tree + break; + } + SEL_ARG *new_arg=tmp->clone_last(&key2_cpy); + if (!new_arg) + return 0; // OOM + tmp->copy_max_to_min(&key2_cpy); + tmp->increment_use_count(key1->use_count+1); + /* Increment key count as it may be used for next loop */ + key2_cpy.increment_use_count(1); + new_arg->next_key_part= key_or(param, tmp->next_key_part, + key2_cpy.next_key_part); + key1=key1->insert(new_arg); + break; + } + } + // Move on to next range in key2 + key2=key2->next; + } + +end: + /* + Add key2 ranges that are non-overlapping with and higher than the + highest range in key1. + */ + while (key2) + { + SEL_ARG *next=key2->next; + if (key2_shared) + { + SEL_ARG *tmp=new SEL_ARG(*key2); // Must make copy + if (!tmp) + return 0; + key2->increment_use_count(key1->use_count+1); + key1=key1->insert(tmp); + } + else + key1=key1->insert(key2); // Will destroy key2_root + key2=next; + } + key1->use_count++; + + /* Re-compute the result tree's weight. */ + key1->update_weight_locally(); + + key1->max_part_no= max_part_no; + return key1; +} + + +/* Compare if two trees are equal */ + +static bool eq_tree(SEL_ARG* a,SEL_ARG *b) +{ + if (a == b) + return 1; + if (!a || !b || !a->is_same(b)) + return 0; + if (a->left != &null_element && b->left != &null_element) + { + if (!eq_tree(a->left,b->left)) + return 0; + } + else if (a->left != &null_element || b->left != &null_element) + return 0; + if (a->right != &null_element && b->right != &null_element) + { + if (!eq_tree(a->right,b->right)) + return 0; + } + else if (a->right != &null_element || b->right != &null_element) + return 0; + if (a->next_key_part != b->next_key_part) + { // Sub range + if (!a->next_key_part != !b->next_key_part || + !eq_tree(a->next_key_part, b->next_key_part)) + return 0; + } + return 1; +} + + +/* + Compute the MAX(key part) in this SEL_ARG graph. +*/ +uint SEL_ARG::get_max_key_part() const +{ + const SEL_ARG *cur; + uint max_part= part; + for (cur= first(); cur ; cur=cur->next) + { + if (cur->next_key_part) + { + uint mp= cur->next_key_part->get_max_key_part(); + max_part= MY_MAX(part, mp); + } + } + return max_part; +} + + +/* + Remove the SEL_ARG graph elements which have part > max_part. + + @detail + Also update weight for the graph and any modified subgraphs. +*/ + +void prune_sel_arg_graph(SEL_ARG *sel_arg, uint max_part) +{ + SEL_ARG *cur; + DBUG_ASSERT(max_part >= sel_arg->part); + + for (cur= sel_arg->first(); cur ; cur=cur->next) + { + if (cur->next_key_part) + { + if (cur->next_key_part->part > max_part) + { + // Remove cur->next_key_part. + sel_arg->weight -= cur->next_key_part->weight; + cur->next_key_part= NULL; + } + else + { + uint old_weight= cur->next_key_part->weight; + prune_sel_arg_graph(cur->next_key_part, max_part); + sel_arg->weight -= (old_weight - cur->next_key_part->weight); + } + } + } +} + + +/* + @brief + Make sure the passed SEL_ARG graph's weight is below SEL_ARG::MAX_WEIGHT, + by cutting off branches if necessary. + + @detail + @see declaration of SEL_ARG::weight for definition of weight. + + This function attempts to reduce the graph's weight by cutting off + SEL_ARG::next_key_part connections if necessary. + + We start with maximum used keypart and then remove one keypart after + another until the graph's weight is within the limit. + + @seealso + sel_arg_and_weight_heuristic(); + + @return + tree pointer The tree after processing, + NULL If it was not possible to reduce the weight of the tree below the + limit. +*/ + +SEL_ARG *enforce_sel_arg_weight_limit(RANGE_OPT_PARAM *param, uint keyno, + SEL_ARG *sel_arg) +{ + if (!sel_arg || sel_arg->type != SEL_ARG::KEY_RANGE || + !param->thd->variables.optimizer_max_sel_arg_weight) + return sel_arg; + + Field *field= sel_arg->field; + uint weight1= sel_arg->weight; + + while (1) + { + if (likely(sel_arg->weight <= param->thd->variables. + optimizer_max_sel_arg_weight)) + break; + + uint max_part= sel_arg->get_max_key_part(); + if (max_part == sel_arg->part) + { + /* + We don't return NULL right away as we want to have the information + about the changed tree in the optimizer trace. + */ + sel_arg= NULL; + break; + } + + max_part--; + prune_sel_arg_graph(sel_arg, max_part); + } + + uint weight2= sel_arg? sel_arg->weight : 0; + + if (weight2 != weight1) + { + Json_writer_object wrapper(param->thd); + Json_writer_object obj(param->thd, "enforce_sel_arg_weight_limit"); + if (param->using_real_indexes) + obj.add("index", param->table->key_info[param->real_keynr[keyno]].name); + else + obj.add("pseudo_index", field->field_name); + + obj.add("old_weight", (longlong)weight1); + obj.add("new_weight", (longlong)weight2); + } + return sel_arg; +} + + +/* + @detail + Do not combine the trees if their total weight is likely to exceed the + MAX_WEIGHT. + (It is possible that key1 has next_key_part that has empty overlap with + key2. In this case, the combined tree will have a smaller weight than we + predict. We assume this is rare.) +*/ + +static +bool sel_arg_and_weight_heuristic(RANGE_OPT_PARAM *param, SEL_ARG *key1, + SEL_ARG *key2) +{ + DBUG_ASSERT(key1->part < key2->part); + + ulong max_weight= param->thd->variables.optimizer_max_sel_arg_weight; + if (max_weight && key1->weight + key1->elements*key2->weight > max_weight) + { + Json_writer_object wrapper(param->thd); + Json_writer_object obj(param->thd, "sel_arg_weight_heuristic"); + obj.add("key1_field", key1->field->field_name); + obj.add("key2_field", key2->field->field_name); + obj.add("key1_weight", (longlong)key1->weight); + obj.add("key2_weight", (longlong)key2->weight); + return true; // Discard key2 + } + return false; +} + + +SEL_ARG * +SEL_ARG::insert(SEL_ARG *key) +{ + SEL_ARG *element,**UNINIT_VAR(par),*UNINIT_VAR(last_element); + + for (element= this; element != &null_element ; ) + { + last_element=element; + if (key->cmp_min_to_min(element) > 0) + { + par= &element->right; element= element->right; + } + else + { + par = &element->left; element= element->left; + } + } + *par=key; + key->parent=last_element; + /* Link in list */ + if (par == &last_element->left) + { + key->next=last_element; + if ((key->prev=last_element->prev)) + key->prev->next=key; + last_element->prev=key; + } + else + { + if ((key->next=last_element->next)) + key->next->prev=key; + key->prev=last_element; + last_element->next=key; + } + key->left=key->right= &null_element; + SEL_ARG *root=rb_insert(key); // rebalance tree + root->use_count=this->use_count; // copy root info + root->elements= this->elements+1; + /* + The new weight is: + old root's weight + +1 for the weight of the added element + + next_key_part's weight of the added element + */ + root->weight = weight + 1 + (key->next_key_part? key->next_key_part->weight: 0); + root->maybe_flag=this->maybe_flag; + return root; +} + + +/* +** Find best key with min <= given key +** Because the call context this should never return 0 to get_range +*/ + +SEL_ARG * +SEL_ARG::find_range(SEL_ARG *key) +{ + SEL_ARG *element=this,*found=0; + + for (;;) + { + if (element == &null_element) + return found; + int cmp=element->cmp_min_to_min(key); + if (cmp == 0) + return element; + if (cmp < 0) + { + found=element; + element=element->right; + } + else + element=element->left; + } +} + + +/* + Remove a element from the tree + + SYNOPSIS + tree_delete() + key Key that is to be deleted from tree (this) + + NOTE + This also frees all sub trees that is used by the element + + RETURN + root of new tree (with key deleted) +*/ + +SEL_ARG * +SEL_ARG::tree_delete(SEL_ARG *key) +{ + enum leaf_color remove_color; + SEL_ARG *root,*nod,**par,*fix_par; + DBUG_ENTER("tree_delete"); + + root=this; + this->parent= 0; + + /* + Compute the weight the tree will have after the element is removed. + We remove the element itself (weight=1) + and the sub-graph connected to its next_key_part. + */ + uint new_weight= root->weight - (1 + (key->next_key_part? + key->next_key_part->weight : 0)); + + DBUG_ASSERT(root->weight >= (1 + (key->next_key_part ? + key->next_key_part->weight : 0))); + + /* Unlink from list */ + if (key->prev) + key->prev->next=key->next; + if (key->next) + key->next->prev=key->prev; + key->increment_use_count(-1); + if (!key->parent) + par= &root; + else + par=key->parent_ptr(); + + if (key->left == &null_element) + { + *par=nod=key->right; + fix_par=key->parent; + if (nod != &null_element) + nod->parent=fix_par; + remove_color= key->color; + } + else if (key->right == &null_element) + { + *par= nod=key->left; + nod->parent=fix_par=key->parent; + remove_color= key->color; + } + else + { + SEL_ARG *tmp=key->next; // next bigger key (exist!) + nod= *tmp->parent_ptr()= tmp->right; // unlink tmp from tree + fix_par=tmp->parent; + if (nod != &null_element) + nod->parent=fix_par; + remove_color= tmp->color; + + tmp->parent=key->parent; // Move node in place of key + (tmp->left=key->left)->parent=tmp; + if ((tmp->right=key->right) != &null_element) + tmp->right->parent=tmp; + tmp->color=key->color; + *par=tmp; + if (fix_par == key) // key->right == key->next + fix_par=tmp; // new parent of nod + } + + if (root == &null_element) + DBUG_RETURN(0); // Maybe root later + if (remove_color == BLACK) + root=rb_delete_fixup(root,nod,fix_par); + test_rb_tree(root,root->parent); + + root->use_count=this->use_count; // Fix root counters + root->weight= new_weight; + root->elements=this->elements-1; + root->maybe_flag=this->maybe_flag; + DBUG_RETURN(root); +} + + + /* Functions to fix up the tree after insert and delete */ + +static void left_rotate(SEL_ARG **root,SEL_ARG *leaf) +{ + SEL_ARG *y=leaf->right; + leaf->right=y->left; + if (y->left != &null_element) + y->left->parent=leaf; + if (!(y->parent=leaf->parent)) + *root=y; + else + *leaf->parent_ptr()=y; + y->left=leaf; + leaf->parent=y; +} + +static void right_rotate(SEL_ARG **root,SEL_ARG *leaf) +{ + SEL_ARG *y=leaf->left; + leaf->left=y->right; + if (y->right != &null_element) + y->right->parent=leaf; + if (!(y->parent=leaf->parent)) + *root=y; + else + *leaf->parent_ptr()=y; + y->right=leaf; + leaf->parent=y; +} + + +SEL_ARG * +SEL_ARG::rb_insert(SEL_ARG *leaf) +{ + SEL_ARG *y,*par,*par2,*root; + root= this; root->parent= 0; + + leaf->color=RED; + while (leaf != root && (par= leaf->parent)->color == RED) + { // This can't be root or 1 level under + if (par == (par2= leaf->parent->parent)->left) + { + y= par2->right; + if (y->color == RED) + { + par->color=BLACK; + y->color=BLACK; + leaf=par2; + leaf->color=RED; /* And the loop continues */ + } + else + { + if (leaf == par->right) + { + left_rotate(&root,leaf->parent); + par=leaf; /* leaf is now parent to old leaf */ + } + par->color=BLACK; + par2->color=RED; + right_rotate(&root,par2); + break; + } + } + else + { + y= par2->left; + if (y->color == RED) + { + par->color=BLACK; + y->color=BLACK; + leaf=par2; + leaf->color=RED; /* And the loop continues */ + } + else + { + if (leaf == par->left) + { + right_rotate(&root,par); + par=leaf; + } + par->color=BLACK; + par2->color=RED; + left_rotate(&root,par2); + break; + } + } + } + root->color=BLACK; + test_rb_tree(root,root->parent); + return root; +} + + +SEL_ARG *rb_delete_fixup(SEL_ARG *root,SEL_ARG *key,SEL_ARG *par) +{ + SEL_ARG *x,*w; + root->parent=0; + + x= key; + while (x != root && x->color == SEL_ARG::BLACK) + { + if (x == par->left) + { + w=par->right; + if (w->color == SEL_ARG::RED) + { + w->color=SEL_ARG::BLACK; + par->color=SEL_ARG::RED; + left_rotate(&root,par); + w=par->right; + } + if (w->left->color == SEL_ARG::BLACK && w->right->color == SEL_ARG::BLACK) + { + w->color=SEL_ARG::RED; + x=par; + } + else + { + if (w->right->color == SEL_ARG::BLACK) + { + w->left->color=SEL_ARG::BLACK; + w->color=SEL_ARG::RED; + right_rotate(&root,w); + w=par->right; + } + w->color=par->color; + par->color=SEL_ARG::BLACK; + w->right->color=SEL_ARG::BLACK; + left_rotate(&root,par); + x=root; + break; + } + } + else + { + w=par->left; + if (w->color == SEL_ARG::RED) + { + w->color=SEL_ARG::BLACK; + par->color=SEL_ARG::RED; + right_rotate(&root,par); + w=par->left; + } + if (w->right->color == SEL_ARG::BLACK && w->left->color == SEL_ARG::BLACK) + { + w->color=SEL_ARG::RED; + x=par; + } + else + { + if (w->left->color == SEL_ARG::BLACK) + { + w->right->color=SEL_ARG::BLACK; + w->color=SEL_ARG::RED; + left_rotate(&root,w); + w=par->left; + } + w->color=par->color; + par->color=SEL_ARG::BLACK; + w->left->color=SEL_ARG::BLACK; + right_rotate(&root,par); + x=root; + break; + } + } + par=x->parent; + } + x->color=SEL_ARG::BLACK; + return root; +} + + + /* Test that the properties for a red-black tree hold */ + +#ifdef EXTRA_DEBUG +int test_rb_tree(SEL_ARG *element,SEL_ARG *parent) +{ + int count_l,count_r; + + if (element == &null_element) + return 0; // Found end of tree + if (element->parent != parent) + { + sql_print_error("Wrong tree: Parent doesn't point at parent"); + return -1; + } + if (element->color == SEL_ARG::RED && + (element->left->color == SEL_ARG::RED || + element->right->color == SEL_ARG::RED)) + { + sql_print_error("Wrong tree: Found two red in a row"); + return -1; + } + if (element->left == element->right && element->left != &null_element) + { // Dummy test + sql_print_error("Wrong tree: Found right == left"); + return -1; + } + count_l=test_rb_tree(element->left,element); + count_r=test_rb_tree(element->right,element); + if (count_l >= 0 && count_r >= 0) + { + if (count_l == count_r) + return count_l+(element->color == SEL_ARG::BLACK); + sql_print_error("Wrong tree: Incorrect black-count: %d - %d", + count_l,count_r); + } + return -1; // Error, no more warnings +} + + +/** + Count how many times SEL_ARG graph "root" refers to its part "key" via + transitive closure. + + @param root An RB-Root node in a SEL_ARG graph. + @param key Another RB-Root node in that SEL_ARG graph. + + The passed "root" node may refer to "key" node via root->next_key_part, + root->next->n + + This function counts how many times the node "key" is referred (via + SEL_ARG::next_key_part) by + - intervals of RB-tree pointed by "root", + - intervals of RB-trees that are pointed by SEL_ARG::next_key_part from + intervals of RB-tree pointed by "root", + - and so on. + + Here is an example (horizontal links represent next_key_part pointers, + vertical links - next/prev prev pointers): + + +----+ $ + |root|-----------------+ + +----+ $ | + | $ | + | $ | + +----+ +---+ $ | +---+ Here the return value + | |- ... -| |---$-+--+->|key| will be 4. + +----+ +---+ $ | | +---+ + | $ | | + ... $ | | + | $ | | + +----+ +---+ $ | | + | |---| |---------+ | + +----+ +---+ $ | + | | $ | + ... +---+ $ | + | |------------+ + +---+ $ + @return + Number of links to "key" from nodes reachable from "root". +*/ + +static ulong count_key_part_usage(SEL_ARG *root, SEL_ARG *key) +{ + ulong count= 0; + for (root=root->first(); root ; root=root->next) + { + if (root->next_key_part) + { + if (root->next_key_part == key) + count++; + if (root->next_key_part->part < key->part) + count+=count_key_part_usage(root->next_key_part,key); + } + } + return count; +} + + +/* + Check if SEL_ARG::use_count value is correct + + SYNOPSIS + SEL_ARG::test_use_count() + root The root node of the SEL_ARG graph (an RB-tree root node that + has the least value of sel_arg->part in the entire graph, and + thus is the "origin" of the graph) + + DESCRIPTION + Check if SEL_ARG::use_count value is correct. See the definition of + use_count for what is "correct". +*/ + +void SEL_ARG::test_use_count(SEL_ARG *root) +{ + uint e_count=0; + + if (this->type != SEL_ARG::KEY_RANGE) + return; + for (SEL_ARG *pos=first(); pos ; pos=pos->next) + { + e_count++; + if (pos->next_key_part) + { + ulong count=count_key_part_usage(root,pos->next_key_part); + if (count > pos->next_key_part->use_count) + { + sql_print_information("Use_count: Wrong count for key at %p: %lu " + "should be %lu", pos, + pos->next_key_part->use_count, count); + return; + } + pos->next_key_part->test_use_count(root); + } + } + if (e_count != elements) + sql_print_warning("Wrong use count: %u (should be %u) for tree at %p", + e_count, elements, this); +} +#endif + +/* + Calculate cost and E(#rows) for a given index and intervals tree + + SYNOPSIS + check_quick_select() + param Parameter from test_quick_select + idx Number of index to use in PARAM::key SEL_TREE::key + index_only TRUE - assume only index tuples will be accessed + FALSE - assume full table rows will be read + tree Transformed selection condition, tree->key[idx] holds + the intervals for the given index. + update_tbl_stats TRUE <=> update table->quick_* with information + about range scan we've evaluated. + mrr_flags INOUT MRR access flags + cost OUT Scan cost + is_ror_scan is set to reflect if the key scan is a ROR (see + is_key_scan_ror function for more info) + + NOTES + param->table->opt_range*, param->range_count (and maybe others) are + updated with data of given key scan, see quick_range_seq_next for details. + + RETURN + Estimate # of records to be retrieved. + HA_POS_ERROR if estimate calculation failed due to table handler problems. +*/ + +static +ha_rows check_quick_select(PARAM *param, uint idx, bool index_only, + SEL_ARG *tree, bool update_tbl_stats, + uint *mrr_flags, uint *bufsize, Cost_estimate *cost, + bool *is_ror_scan) +{ + SEL_ARG_RANGE_SEQ seq; + RANGE_SEQ_IF seq_if = {NULL, sel_arg_range_seq_init, sel_arg_range_seq_next, 0, 0}; + handler *file= param->table->file; + ha_rows rows= HA_POS_ERROR; + uint keynr= param->real_keynr[idx]; + DBUG_ENTER("check_quick_select"); + + /* Range not calculated yet */ + param->quick_rows[keynr]= HA_POS_ERROR; + + /* Handle cases when we don't have a valid non-empty list of range */ + if (!tree) + DBUG_RETURN(HA_POS_ERROR); + if (tree->type == SEL_ARG::IMPOSSIBLE) + DBUG_RETURN(0L); + if (tree->type != SEL_ARG::KEY_RANGE || tree->part != 0) + DBUG_RETURN(HA_POS_ERROR); + + seq.keyno= idx; + seq.real_keyno= keynr; + seq.param= param; + seq.start= tree; + + param->range_count=0; + param->max_key_parts=0; + + seq.is_ror_scan= TRUE; + if (file->index_flags(keynr, 0, TRUE) & HA_KEY_SCAN_NOT_ROR) + seq.is_ror_scan= FALSE; + + *mrr_flags= param->force_default_mrr? HA_MRR_USE_DEFAULT_IMPL: 0; + /* + Pass HA_MRR_SORTED to see if MRR implementation can handle sorting. + */ + *mrr_flags|= HA_MRR_NO_ASSOCIATION | HA_MRR_SORTED; + + // TODO: param->max_key_parts holds 0 now, and not the #keyparts used. + // Passing wrong second argument to index_flags() makes no difference for + // most storage engines but might be an issue for MyRocks with certain + // datatypes. + if (index_only && + (file->index_flags(keynr, param->max_key_parts, 1) & HA_KEYREAD_ONLY) && + !(file->index_flags(keynr, param->max_key_parts, 1) & HA_CLUSTERED_INDEX)) + *mrr_flags |= HA_MRR_INDEX_ONLY; + + if (param->thd->lex->sql_command != SQLCOM_SELECT) + *mrr_flags |= HA_MRR_USE_DEFAULT_IMPL; + + *bufsize= param->thd->variables.mrr_buff_size; + /* + Skip materialized derived table/view result table from MRR check as + they aren't contain any data yet. + */ + if (param->table->pos_in_table_list->is_non_derived()) + rows= file->multi_range_read_info_const(keynr, &seq_if, (void*)&seq, 0, + bufsize, mrr_flags, cost); + param->quick_rows[keynr]= rows; + if (rows != HA_POS_ERROR) + { + ha_rows table_records= param->table->stat_records(); + if (rows > table_records) + { + /* + For any index the total number of records within all ranges + cannot be be bigger than the number of records in the table. + This check is needed as sometimes that table statistics or range + estimates may be slightly out of sync. + */ + rows= table_records; + set_if_bigger(rows, 1); + param->quick_rows[keynr]= rows; + } + param->possible_keys.set_bit(keynr); + if (update_tbl_stats) + { + param->table->opt_range_keys.set_bit(keynr); + param->table->opt_range[keynr].key_parts= param->max_key_parts; + param->table->opt_range[keynr].ranges= param->range_count; + param->table->opt_range_condition_rows= + MY_MIN(param->table->opt_range_condition_rows, rows); + param->table->opt_range[keynr].rows= rows; + param->table->opt_range[keynr].cost= cost->total_cost(); + if (param->table->file->is_clustering_key(keynr)) + param->table->opt_range[keynr].index_only_cost= 0; + else + param->table->opt_range[keynr].index_only_cost= cost->index_only_cost(); + } + } + + /* Figure out if the key scan is ROR (returns rows in ROWID order) or not */ + enum ha_key_alg key_alg= param->table->key_info[seq.real_keyno].algorithm; + if ((key_alg != HA_KEY_ALG_BTREE) && (key_alg!= HA_KEY_ALG_UNDEF)) + { + /* + All scans are non-ROR scans for those index types. + TODO: Don't have this logic here, make table engines return + appropriate flags instead. + */ + seq.is_ror_scan= FALSE; + } + else if (param->table->file->is_clustering_key(keynr)) + { + /* Clustered PK scan is always a ROR scan (TODO: same as above) */ + seq.is_ror_scan= TRUE; + } + else if (param->range_count > 1) + { + /* + Scaning multiple key values in the index: the records are ROR + for each value, but not between values. E.g, "SELECT ... x IN + (1,3)" returns ROR order for all records with x=1, then ROR + order for records with x=3 + */ + seq.is_ror_scan= FALSE; + } + *is_ror_scan= seq.is_ror_scan; + + DBUG_PRINT("exit", ("Records: %lu", (ulong) rows)); + DBUG_RETURN(rows); //psergey-merge:todo: maintain first_null_comp. +} + + +/* + Check if key scan on given index with equality conditions on first n key + parts is a ROR scan. + + SYNOPSIS + is_key_scan_ror() + param Parameter from test_quick_select + keynr Number of key in the table. The key must not be a clustered + primary key. + nparts Number of first key parts for which equality conditions + are present. + + NOTES + ROR (Rowid Ordered Retrieval) key scan is a key scan that produces + ordered sequence of rowids (ha_xxx::cmp_ref is the comparison function) + + This function is needed to handle a practically-important special case: + an index scan is a ROR scan if it is done using a condition in form + + "key1_1=c_1 AND ... AND key1_n=c_n" + + where the index is defined on (key1_1, ..., key1_N [,a_1, ..., a_n]) + + and the table has a clustered Primary Key defined as + PRIMARY KEY(a_1, ..., a_n, b1, ..., b_k) + + i.e. the first key parts of it are identical to uncovered parts ot the + key being scanned. This function assumes that the index flags do not + include HA_KEY_SCAN_NOT_ROR flag (that is checked elsewhere). + + Check (1) is made in quick_range_seq_next() + + RETURN + TRUE The scan is ROR-scan + FALSE Otherwise +*/ + +static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts) +{ + KEY *table_key= param->table->key_info + keynr; + KEY_PART_INFO *key_part= table_key->key_part + nparts; + KEY_PART_INFO *key_part_end= (table_key->key_part + + table_key->user_defined_key_parts); + uint pk_number; + + for (KEY_PART_INFO *kp= table_key->key_part; kp < key_part; kp++) + { + uint16 fieldnr= param->table->key_info[keynr]. + key_part[kp - table_key->key_part].fieldnr - 1; + if (param->table->field[fieldnr]->key_length() != kp->length) + return FALSE; + } + + /* + If there are equalities for all key parts, it is a ROR scan. If there are + equalities all keyparts and even some of key parts from "Extended Key" + index suffix, it is a ROR-scan, too. + */ + if (key_part >= key_part_end) + return TRUE; + + key_part= table_key->key_part + nparts; + pk_number= param->table->s->primary_key; + if (!param->table->file->pk_is_clustering_key(pk_number)) + return FALSE; + + KEY_PART_INFO *pk_part= param->table->key_info[pk_number].key_part; + KEY_PART_INFO *pk_part_end= pk_part + + param->table->key_info[pk_number].user_defined_key_parts; + for (;(key_part!=key_part_end) && (pk_part != pk_part_end); + ++key_part, ++pk_part) + { + if ((key_part->field != pk_part->field) || + (key_part->length != pk_part->length)) + return FALSE; + } + return (key_part == key_part_end); +} + + +/* + Create a QUICK_RANGE_SELECT from given key and SEL_ARG tree for that key. + + SYNOPSIS + get_quick_select() + param + idx Index of used key in param->key. + key_tree SEL_ARG tree for the used key + mrr_flags MRR parameter for quick select + mrr_buf_size MRR parameter for quick select + parent_alloc If not NULL, use it to allocate memory for + quick select data. Otherwise use quick->alloc. + NOTES + The caller must call QUICK_SELECT::init for returned quick select. + + CAUTION! This function may change thd->mem_root to a MEM_ROOT which will be + deallocated when the returned quick select is deleted. + + RETURN + NULL on error + otherwise created quick select +*/ + +QUICK_RANGE_SELECT * +get_quick_select(PARAM *param,uint idx,SEL_ARG *key_tree, uint mrr_flags, + uint mrr_buf_size, MEM_ROOT *parent_alloc) +{ + QUICK_RANGE_SELECT *quick; + bool create_err= FALSE; + DBUG_ENTER("get_quick_select"); + + if (param->table->key_info[param->real_keynr[idx]].flags & HA_SPATIAL) + quick=new QUICK_RANGE_SELECT_GEOM(param->thd, param->table, + param->real_keynr[idx], + MY_TEST(parent_alloc), + parent_alloc, &create_err); + else + quick=new QUICK_RANGE_SELECT(param->thd, param->table, + param->real_keynr[idx], + MY_TEST(parent_alloc), NULL, &create_err); + + if (quick) + { + if (create_err || + get_quick_keys(param,quick,param->key[idx],key_tree,param->min_key,0, + param->max_key,0)) + { + delete quick; + quick=0; + } + else + { + KEY *keyinfo= param->table->key_info+param->real_keynr[idx]; + quick->mrr_flags= mrr_flags; + quick->mrr_buf_size= mrr_buf_size; + quick->key_parts=(KEY_PART*) + memdup_root(parent_alloc? parent_alloc : &quick->alloc, + (char*) param->key[idx], + sizeof(KEY_PART)* + param->table->actual_n_key_parts(keyinfo)); + } + } + DBUG_RETURN(quick); +} + + +/* +** Fix this to get all possible sub_ranges +*/ +bool +get_quick_keys(PARAM *param,QUICK_RANGE_SELECT *quick,KEY_PART *key, + SEL_ARG *key_tree, uchar *min_key,uint min_key_flag, + uchar *max_key, uint max_key_flag) +{ + QUICK_RANGE *range; + uint flag; + int min_part= key_tree->part-1, // # of keypart values in min_key buffer + max_part= key_tree->part-1; // # of keypart values in max_key buffer + + if (key_tree->left != &null_element) + { + if (get_quick_keys(param,quick,key,key_tree->left, + min_key,min_key_flag, max_key, max_key_flag)) + return 1; + } + uchar *tmp_min_key=min_key,*tmp_max_key=max_key; + min_part+= key_tree->store_min(key[key_tree->part].store_length, + &tmp_min_key,min_key_flag); + max_part+= key_tree->store_max(key[key_tree->part].store_length, + &tmp_max_key,max_key_flag); + + if (key_tree->next_key_part && + key_tree->next_key_part->type == SEL_ARG::KEY_RANGE && + key_tree->next_key_part->part == key_tree->part+1) + { // const key as prefix + if ((tmp_min_key - min_key) == (tmp_max_key - max_key) && + memcmp(min_key, max_key, (uint)(tmp_max_key - max_key))==0 && + key_tree->min_flag==0 && key_tree->max_flag==0) + { + if (get_quick_keys(param,quick,key,key_tree->next_key_part, + tmp_min_key, min_key_flag | key_tree->min_flag, + tmp_max_key, max_key_flag | key_tree->max_flag)) + return 1; + goto end; // Ugly, but efficient + } + { + uint tmp_min_flag=key_tree->min_flag,tmp_max_flag=key_tree->max_flag; + if (!tmp_min_flag) + min_part+= key_tree->next_key_part->store_min_key(key, + &tmp_min_key, + &tmp_min_flag, + MAX_KEY); + if (!tmp_max_flag) + max_part+= key_tree->next_key_part->store_max_key(key, + &tmp_max_key, + &tmp_max_flag, + MAX_KEY); + flag=tmp_min_flag | tmp_max_flag; + } + } + else + { + flag = (key_tree->min_flag & GEOM_FLAG) ? + key_tree->min_flag : key_tree->min_flag | key_tree->max_flag; + } + + /* + Ensure that some part of min_key and max_key are used. If not, + regard this as no lower/upper range + */ + if ((flag & GEOM_FLAG) == 0) + { + if (tmp_min_key != param->min_key) + flag&= ~NO_MIN_RANGE; + else + flag|= NO_MIN_RANGE; + if (tmp_max_key != param->max_key) + flag&= ~NO_MAX_RANGE; + else + flag|= NO_MAX_RANGE; + } + if (flag == 0) + { + uint length= (uint) (tmp_min_key - param->min_key); + if (length == (uint) (tmp_max_key - param->max_key) && + !memcmp(param->min_key,param->max_key,length)) + { + KEY *table_key=quick->head->key_info+quick->index; + flag=EQ_RANGE; + if ((table_key->flags & HA_NOSAME) && + min_part == key_tree->part && + key_tree->part == table_key->user_defined_key_parts-1) + { + DBUG_ASSERT(min_part == max_part); + if ((table_key->flags & HA_NULL_PART_KEY) && + null_part_in_key(key, + param->min_key, + (uint) (tmp_min_key - param->min_key))) + flag|= NULL_RANGE; + else + flag|= UNIQUE_RANGE; + } + } + } + + /* Get range for retrieving rows in QUICK_SELECT::get_next */ + if (!(range= new (param->thd->mem_root) QUICK_RANGE( + param->thd, + param->min_key, + (uint) (tmp_min_key - param->min_key), + min_part >=0 ? make_keypart_map(min_part) : 0, + param->max_key, + (uint) (tmp_max_key - param->max_key), + max_part >=0 ? make_keypart_map(max_part) : 0, + flag))) + return 1; // out of memory + + set_if_bigger(quick->max_used_key_length, range->min_length); + set_if_bigger(quick->max_used_key_length, range->max_length); + set_if_bigger(quick->used_key_parts, (uint) key_tree->part+1); + if (insert_dynamic(&quick->ranges, (uchar*) &range)) + return 1; + + end: + if (key_tree->right != &null_element) + return get_quick_keys(param,quick,key,key_tree->right, + min_key,min_key_flag, + max_key,max_key_flag); + return 0; +} + +/* + Return 1 if there is only one range and this uses the whole unique key +*/ + +bool QUICK_RANGE_SELECT::unique_key_range() +{ + if (ranges.elements == 1) + { + QUICK_RANGE *tmp= *((QUICK_RANGE**)ranges.buffer); + if ((tmp->flag & (EQ_RANGE | NULL_RANGE)) == EQ_RANGE) + { + KEY *key=head->key_info+index; + return (key->flags & HA_NOSAME) && key->key_length == tmp->min_length; + } + } + return 0; +} + + + +/* + Return TRUE if any part of the key is NULL + + SYNOPSIS + null_part_in_key() + key_part Array of key parts (index description) + key Key values tuple + length Length of key values tuple in bytes. + + RETURN + TRUE The tuple has at least one "keypartX is NULL" + FALSE Otherwise +*/ + +static bool null_part_in_key(KEY_PART *key_part, const uchar *key, uint length) +{ + for (const uchar *end=key+length ; + key < end; + key+= key_part++->store_length) + { + if (key_part->null_bit && *key) + return 1; + } + return 0; +} + + +bool QUICK_SELECT_I::is_keys_used(const MY_BITMAP *fields) +{ + return is_key_used(head, index, fields); +} + +bool QUICK_INDEX_SORT_SELECT::is_keys_used(const MY_BITMAP *fields) +{ + QUICK_RANGE_SELECT *quick; + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + while ((quick= it++)) + { + if (is_key_used(head, quick->index, fields)) + return 1; + } + return 0; +} + +bool QUICK_ROR_INTERSECT_SELECT::is_keys_used(const MY_BITMAP *fields) +{ + QUICK_SELECT_WITH_RECORD *qr; + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + while ((qr= it++)) + { + if (is_key_used(head, qr->quick->index, fields)) + return 1; + } + return 0; +} + +bool QUICK_ROR_UNION_SELECT::is_keys_used(const MY_BITMAP *fields) +{ + QUICK_SELECT_I *quick; + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + while ((quick= it++)) + { + if (quick->is_keys_used(fields)) + return 1; + } + return 0; +} + + +FT_SELECT *get_ft_select(THD *thd, TABLE *table, uint key) +{ + bool create_err= FALSE; + FT_SELECT *fts= new FT_SELECT(thd, table, key, &create_err); + if (create_err) + { + delete fts; + return NULL; + } + else + return fts; +} + +/* + Create quick select from ref/ref_or_null scan. + + SYNOPSIS + get_quick_select_for_ref() + thd Thread handle + table Table to access + ref ref[_or_null] scan parameters + records Estimate of number of records (needed only to construct + quick select) + NOTES + This allocates things in a new memory root, as this may be called many + times during a query. + + RETURN + Quick select that retrieves the same rows as passed ref scan + NULL on error. +*/ + +QUICK_RANGE_SELECT *get_quick_select_for_ref(THD *thd, TABLE *table, + TABLE_REF *ref, ha_rows records) +{ + MEM_ROOT *old_root, *alloc; + QUICK_RANGE_SELECT *quick; + KEY *key_info = &table->key_info[ref->key]; + KEY_PART *key_part; + QUICK_RANGE *range; + uint part; + bool create_err= FALSE; + Cost_estimate cost; + uint max_used_key_len; + + old_root= thd->mem_root; + /* The following call may change thd->mem_root */ + quick= new QUICK_RANGE_SELECT(thd, table, ref->key, 0, 0, &create_err); + /* save mem_root set by QUICK_RANGE_SELECT constructor */ + alloc= thd->mem_root; + /* + return back default mem_root (thd->mem_root) changed by + QUICK_RANGE_SELECT constructor + */ + thd->mem_root= old_root; + + if (!quick || create_err || quick->init()) + goto err; + quick->records= records; + + if ((cp_buffer_from_ref(thd, table, ref) && + unlikely(thd->is_fatal_error)) || + unlikely(!(range= new(alloc) QUICK_RANGE()))) + goto err; // out of memory + + range->min_key= range->max_key= ref->key_buff; + range->min_length= range->max_length= ref->key_length; + range->min_keypart_map= range->max_keypart_map= + make_prev_keypart_map(ref->key_parts); + range->flag= EQ_RANGE; + + if (unlikely(!(quick->key_parts=key_part=(KEY_PART *) + alloc_root(&quick->alloc,sizeof(KEY_PART)*ref->key_parts)))) + goto err; + + max_used_key_len=0; + for (part=0 ; part < ref->key_parts ;part++,key_part++) + { + key_part->part=part; + key_part->field= key_info->key_part[part].field; + key_part->length= key_info->key_part[part].length; + key_part->store_length= key_info->key_part[part].store_length; + key_part->null_bit= key_info->key_part[part].null_bit; + key_part->flag= (uint8) key_info->key_part[part].key_part_flag; + + max_used_key_len +=key_info->key_part[part].store_length; + } + + quick->max_used_key_length= max_used_key_len; + + if (insert_dynamic(&quick->ranges,(uchar*)&range)) + goto err; + + /* + Add a NULL range if REF_OR_NULL optimization is used. + For example: + if we have "WHERE A=2 OR A IS NULL" we created the (A=2) range above + and have ref->null_ref_key set. Will create a new NULL range here. + */ + if (ref->null_ref_key) + { + QUICK_RANGE *null_range; + + *ref->null_ref_key= 1; // Set null byte then create a range + if (!(null_range= new (alloc) + QUICK_RANGE(thd, ref->key_buff, ref->key_length, + make_prev_keypart_map(ref->key_parts), + ref->key_buff, ref->key_length, + make_prev_keypart_map(ref->key_parts), EQ_RANGE))) + goto err; + *ref->null_ref_key= 0; // Clear null byte + if (insert_dynamic(&quick->ranges,(uchar*)&null_range)) + goto err; + } + + /* Call multi_range_read_info() to get the MRR flags and buffer size */ + quick->mrr_flags= HA_MRR_NO_ASSOCIATION | + (table->file->keyread_enabled() ? HA_MRR_INDEX_ONLY : 0); + if (thd->lex->sql_command != SQLCOM_SELECT) + quick->mrr_flags |= HA_MRR_USE_DEFAULT_IMPL; + + quick->mrr_buf_size= thd->variables.mrr_buff_size; + if (table->file->multi_range_read_info(quick->index, 1, (uint)records, + ~0, + &quick->mrr_buf_size, + &quick->mrr_flags, &cost)) + goto err; + + return quick; +err: + delete quick; + return 0; +} + + +/* + Perform key scans for all used indexes (except CPK), get rowids and merge + them into an ordered non-recurrent sequence of rowids. + + The merge/duplicate removal is performed using Unique class. We put all + rowids into Unique, get the sorted sequence and destroy the Unique. + + If table has a clustered primary key that covers all rows (TRUE for bdb + and innodb currently) and one of the index_merge scans is a scan on PK, + then rows that will be retrieved by PK scan are not put into Unique and + primary key scan is not performed here, it is performed later separately. + + RETURN + 0 OK + other error +*/ + +int read_keys_and_merge_scans(THD *thd, + TABLE *head, + List<QUICK_RANGE_SELECT> quick_selects, + QUICK_RANGE_SELECT *pk_quick_select, + READ_RECORD *read_record, + bool intersection, + key_map *filtered_scans, + Unique **unique_ptr) +{ + List_iterator_fast<QUICK_RANGE_SELECT> cur_quick_it(quick_selects); + QUICK_RANGE_SELECT* cur_quick; + int result; + Unique *unique= *unique_ptr; + handler *file= head->file; + bool with_cpk_filter= pk_quick_select != NULL; + DBUG_ENTER("read_keys_and_merge"); + + /* We're going to just read rowids. */ + head->prepare_for_position(); + + cur_quick_it.rewind(); + cur_quick= cur_quick_it++; + bool first_quick= TRUE; + DBUG_ASSERT(cur_quick != 0); + head->file->ha_start_keyread(cur_quick->index); + + /* + We reuse the same instance of handler so we need to call both init and + reset here. + */ + if (cur_quick->init() || cur_quick->reset()) + goto err; + + if (unique == NULL) + { + DBUG_EXECUTE_IF("index_merge_may_not_create_a_Unique", DBUG_SUICIDE(); ); + DBUG_EXECUTE_IF("only_one_Unique_may_be_created", + DBUG_SET("+d,index_merge_may_not_create_a_Unique"); ); + + unique= new Unique(refpos_order_cmp, (void *)file, + file->ref_length, + (size_t)thd->variables.sortbuff_size, + intersection ? quick_selects.elements : 0); + if (!unique) + goto err; + *unique_ptr= unique; + } + else + { + unique->reset(); + } + + DBUG_ASSERT(file->ref_length == unique->get_size()); + DBUG_ASSERT(thd->variables.sortbuff_size == unique->get_max_in_memory_size()); + + for (;;) + { + while ((result= cur_quick->get_next()) == HA_ERR_END_OF_FILE) + { + if (intersection) + with_cpk_filter= filtered_scans->is_set(cur_quick->index); + if (first_quick) + { + first_quick= FALSE; + if (intersection && unique->is_in_memory()) + unique->close_for_expansion(); + } + cur_quick->range_end(); + cur_quick= cur_quick_it++; + if (!cur_quick) + break; + + if (cur_quick->file->inited != handler::NONE) + cur_quick->file->ha_index_end(); + if (cur_quick->init() || cur_quick->reset()) + goto err; + } + + if (result) + { + if (result != HA_ERR_END_OF_FILE) + { + cur_quick->range_end(); + goto err; + } + break; + } + + if (thd->killed) + goto err; + + if (with_cpk_filter && + pk_quick_select->row_in_ranges() != intersection ) + continue; + + cur_quick->file->position(cur_quick->record); + if (unique->unique_add((char*)cur_quick->file->ref)) + goto err; + } + + /* + Ok all rowids are in the Unique now. The next call will initialize + the unique structure so it can be used to iterate through the rowids + sequence. + */ + result= unique->get(head); + /* + index merge currently doesn't support "using index" at all + */ + head->file->ha_end_keyread(); + if (init_read_record(read_record, thd, head, (SQL_SELECT*) 0, + &unique->sort, 1 , 1, TRUE)) + result= 1; + DBUG_RETURN(result); + +err: + head->file->ha_end_keyread(); + DBUG_RETURN(1); +} + + +int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge() + +{ + int result; + DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::read_keys_and_merge"); + result= read_keys_and_merge_scans(thd, head, quick_selects, pk_quick_select, + &read_record, FALSE, NULL, &unique); + doing_pk_scan= FALSE; + DBUG_RETURN(result); +} + +/* + Get next row for index_merge. + NOTES + The rows are read from + 1. rowids stored in Unique. + 2. QUICK_RANGE_SELECT with clustered primary key (if any). + The sets of rows retrieved in 1) and 2) are guaranteed to be disjoint. +*/ + +int QUICK_INDEX_MERGE_SELECT::get_next() +{ + int result; + DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::get_next"); + + if (doing_pk_scan) + DBUG_RETURN(pk_quick_select->get_next()); + + if ((result= read_record.read_record()) == -1) + { + result= HA_ERR_END_OF_FILE; + end_read_record(&read_record); + // Free things used by sort early. Shouldn't be strictly necessary + unique->sort.reset(); + /* All rows from Unique have been retrieved, do a clustered PK scan */ + if (pk_quick_select) + { + doing_pk_scan= TRUE; + if ((result= pk_quick_select->init()) || + (result= pk_quick_select->reset())) + DBUG_RETURN(result); + DBUG_RETURN(pk_quick_select->get_next()); + } + } + + DBUG_RETURN(result); +} + +int QUICK_INDEX_INTERSECT_SELECT::read_keys_and_merge() + +{ + int result; + DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::read_keys_and_merge"); + result= read_keys_and_merge_scans(thd, head, quick_selects, pk_quick_select, + &read_record, TRUE, &filtered_scans, + &unique); + DBUG_RETURN(result); +} + +int QUICK_INDEX_INTERSECT_SELECT::get_next() +{ + int result; + DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::get_next"); + + if ((result= read_record.read_record()) == -1) + { + result= HA_ERR_END_OF_FILE; + end_read_record(&read_record); + unique->sort.reset(); // Free things early + } + + DBUG_RETURN(result); +} + + +/* + Retrieve next record. + SYNOPSIS + QUICK_ROR_INTERSECT_SELECT::get_next() + + NOTES + Invariant on enter/exit: all intersected selects have retrieved all index + records with rowid <= some_rowid_val and no intersected select has + retrieved any index records with rowid > some_rowid_val. + We start fresh and loop until we have retrieved the same rowid in each of + the key scans or we got an error. + + If a Clustered PK scan is present, it is used only to check if row + satisfies its condition (and never used for row retrieval). + + Locking: to ensure that exclusive locks are only set on records that + are included in the final result we must release the lock + on all rows we read but do not include in the final result. This + must be done on each index that reads the record and the lock + must be released using the same handler (the same quick object) as + used when reading the record. + + RETURN + 0 - Ok + other - Error code if any error occurred. +*/ + +int QUICK_ROR_INTERSECT_SELECT::get_next() +{ + List_iterator_fast<QUICK_SELECT_WITH_RECORD> quick_it(quick_selects); + QUICK_SELECT_WITH_RECORD *qr; + QUICK_RANGE_SELECT* quick; + + /* quick that reads the given rowid first. This is needed in order + to be able to unlock the row using the same handler object that locked + it */ + QUICK_RANGE_SELECT* quick_with_last_rowid; + + int error, cmp; + uint last_rowid_count=0; + DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::get_next"); + + /* Get a rowid for first quick and save it as a 'candidate' */ + qr= quick_it++; + quick= qr->quick; + error= quick->get_next(); + if (cpk_quick) + { + while (!error && !cpk_quick->row_in_ranges()) + { + quick->file->unlock_row(); /* row not in range; unlock */ + error= quick->get_next(); + } + } + if (unlikely(error)) + DBUG_RETURN(error); + + /* Save the read key tuple */ + key_copy(qr->key_tuple, record, head->key_info + quick->index, + quick->max_used_key_length); + + quick->file->position(quick->record); + memcpy(last_rowid, quick->file->ref, head->file->ref_length); + last_rowid_count= 1; + quick_with_last_rowid= quick; + + while (last_rowid_count < quick_selects.elements) + { + if (!(qr= quick_it++)) + { + quick_it.rewind(); + qr= quick_it++; + } + quick= qr->quick; + + do + { + DBUG_EXECUTE_IF("innodb_quick_report_deadlock", + DBUG_SET("+d,innodb_report_deadlock");); + if (unlikely((error= quick->get_next()))) + { + /* On certain errors like deadlock, trx might be rolled back.*/ + if (!thd->transaction_rollback_request) + quick_with_last_rowid->file->unlock_row(); + DBUG_RETURN(error); + } + quick->file->position(quick->record); + cmp= head->file->cmp_ref(quick->file->ref, last_rowid); + if (cmp < 0) + { + /* This row is being skipped. Release lock on it. */ + quick->file->unlock_row(); + } + } while (cmp < 0); + + key_copy(qr->key_tuple, record, head->key_info + quick->index, + quick->max_used_key_length); + + /* Ok, current select 'caught up' and returned ref >= cur_ref */ + if (cmp > 0) + { + /* Found a row with ref > cur_ref. Make it a new 'candidate' */ + if (cpk_quick) + { + while (!cpk_quick->row_in_ranges()) + { + quick->file->unlock_row(); /* row not in range; unlock */ + if (unlikely((error= quick->get_next()))) + { + /* On certain errors like deadlock, trx might be rolled back.*/ + if (!thd->transaction_rollback_request) + quick_with_last_rowid->file->unlock_row(); + DBUG_RETURN(error); + } + } + quick->file->position(quick->record); + } + memcpy(last_rowid, quick->file->ref, head->file->ref_length); + quick_with_last_rowid->file->unlock_row(); + last_rowid_count= 1; + quick_with_last_rowid= quick; + + //save the fields here + key_copy(qr->key_tuple, record, head->key_info + quick->index, + quick->max_used_key_length); + } + else + { + /* current 'candidate' row confirmed by this select */ + last_rowid_count++; + } + } + + /* We get here if we got the same row ref in all scans. */ + if (need_to_fetch_row) + error= head->file->ha_rnd_pos(head->record[0], last_rowid); + + if (!need_to_fetch_row) + { + /* Restore the columns we've read/saved with other quick selects */ + quick_it.rewind(); + while ((qr= quick_it++)) + { + if (qr->quick != quick) + { + key_restore(record, qr->key_tuple, head->key_info + qr->quick->index, + qr->quick->max_used_key_length); + } + } + } + + DBUG_RETURN(error); +} + + +/* + Retrieve next record. + SYNOPSIS + QUICK_ROR_UNION_SELECT::get_next() + + NOTES + Enter/exit invariant: + For each quick select in the queue a {key,rowid} tuple has been + retrieved but the corresponding row hasn't been passed to output. + + RETURN + 0 - Ok + other - Error code if any error occurred. +*/ + +int QUICK_ROR_UNION_SELECT::get_next() +{ + int error, dup_row; + QUICK_SELECT_I *quick; + uchar *tmp; + DBUG_ENTER("QUICK_ROR_UNION_SELECT::get_next"); + + do + { + if (!queue.elements) + DBUG_RETURN(HA_ERR_END_OF_FILE); + /* Ok, we have a queue with >= 1 scans */ + + quick= (QUICK_SELECT_I*)queue_top(&queue); + memcpy(cur_rowid, quick->last_rowid, rowid_length); + + /* put into queue rowid from the same stream as top element */ + if ((error= quick->get_next())) + { + if (error != HA_ERR_END_OF_FILE) + DBUG_RETURN(error); + queue_remove_top(&queue); + } + else + { + quick->save_last_pos(); + queue_replace_top(&queue); + } + + if (!have_prev_rowid) + { + /* No rows have been returned yet */ + dup_row= FALSE; + have_prev_rowid= TRUE; + } + else + dup_row= !head->file->cmp_ref(cur_rowid, prev_rowid); + } while (dup_row); + + tmp= cur_rowid; + cur_rowid= prev_rowid; + prev_rowid= tmp; + + error= head->file->ha_rnd_pos(quick->record, prev_rowid); + DBUG_RETURN(error); +} + + +int QUICK_RANGE_SELECT::reset() +{ + uint buf_size; + uchar *mrange_buff; + int error; + HANDLER_BUFFER empty_buf; + MY_BITMAP * const save_read_set= head->read_set; + MY_BITMAP * const save_write_set= head->write_set; + DBUG_ENTER("QUICK_RANGE_SELECT::reset"); + last_range= NULL; + cur_range= (QUICK_RANGE**) ranges.buffer; + RANGE_SEQ_IF seq_funcs= {NULL, quick_range_seq_init, quick_range_seq_next, 0, 0}; + + if (file->inited == handler::RND) + { + /* Handler could be left in this state by MRR */ + if (unlikely((error= file->ha_rnd_end()))) + DBUG_RETURN(error); + } + + if (in_ror_merged_scan) + head->column_bitmaps_set_no_signal(&column_bitmap, &column_bitmap); + + if (file->inited == handler::NONE) + { + DBUG_EXECUTE_IF("bug14365043_2", + DBUG_SET("+d,ha_index_init_fail");); + if (unlikely((error= file->ha_index_init(index,1)))) + { + file->print_error(error, MYF(0)); + goto err; + } + } + + /* Allocate buffer if we need one but haven't allocated it yet */ + if (mrr_buf_size && !mrr_buf_desc) + { + buf_size= mrr_buf_size; + while (buf_size && !my_multi_malloc(key_memory_QUICK_RANGE_SELECT_mrr_buf_desc, + MYF(MY_WME), + &mrr_buf_desc, sizeof(*mrr_buf_desc), + &mrange_buff, buf_size, + NullS)) + { + /* Try to shrink the buffers until both are 0. */ + buf_size/= 2; + } + if (!mrr_buf_desc) + { + error= HA_ERR_OUT_OF_MEM; + goto err; + } + + /* Initialize the handler buffer. */ + mrr_buf_desc->buffer= mrange_buff; + mrr_buf_desc->buffer_end= mrange_buff + buf_size; + mrr_buf_desc->end_of_used_area= mrange_buff; + } + + if (!mrr_buf_desc) + empty_buf.buffer= empty_buf.buffer_end= empty_buf.end_of_used_area= NULL; + + error= file->multi_range_read_init(&seq_funcs, (void*)this, ranges.elements, + mrr_flags, mrr_buf_desc? mrr_buf_desc: + &empty_buf); +err: + /* Restore bitmaps set on entry */ + if (in_ror_merged_scan) + head->column_bitmaps_set_no_signal(save_read_set, save_write_set); + DBUG_RETURN(error); +} + + +/* + Get next possible record using quick-struct. + + SYNOPSIS + QUICK_RANGE_SELECT::get_next() + + NOTES + Record is read into table->record[0] + + RETURN + 0 Found row + HA_ERR_END_OF_FILE No (more) rows in range + # Error code +*/ + +int QUICK_RANGE_SELECT::get_next() +{ + range_id_t dummy; + int result; + DBUG_ENTER("QUICK_RANGE_SELECT::get_next"); + + if (!in_ror_merged_scan) + DBUG_RETURN(file->multi_range_read_next(&dummy)); + + MY_BITMAP * const save_read_set= head->read_set; + MY_BITMAP * const save_write_set= head->write_set; + /* + We don't need to signal the bitmap change as the bitmap is always the + same for this head->file + */ + head->column_bitmaps_set_no_signal(&column_bitmap, &column_bitmap); + result= file->multi_range_read_next(&dummy); + head->column_bitmaps_set_no_signal(save_read_set, save_write_set); + DBUG_RETURN(result); +} + + +/* + Get the next record with a different prefix. + + @param prefix_length length of cur_prefix + @param group_key_parts The number of key parts in the group prefix + @param cur_prefix prefix of a key to be searched for + + Each subsequent call to the method retrieves the first record that has a + prefix with length prefix_length and which is different from cur_prefix, + such that the record with the new prefix is within the ranges described by + this->ranges. The record found is stored into the buffer pointed by + this->record. The method is useful for GROUP-BY queries with range + conditions to discover the prefix of the next group that satisfies the range + conditions. + + @todo + + This method is a modified copy of QUICK_RANGE_SELECT::get_next(), so both + methods should be unified into a more general one to reduce code + duplication. + + @retval 0 on success + @retval HA_ERR_END_OF_FILE if returned all keys + @retval other if some error occurred +*/ + +int QUICK_RANGE_SELECT::get_next_prefix(uint prefix_length, + uint group_key_parts, + uchar *cur_prefix) +{ + DBUG_ENTER("QUICK_RANGE_SELECT::get_next_prefix"); + const key_part_map keypart_map= make_prev_keypart_map(group_key_parts); + + for (;;) + { + int result; + if (last_range) + { + /* Read the next record in the same range with prefix after cur_prefix. */ + DBUG_ASSERT(cur_prefix != NULL); + result= file->ha_index_read_map(record, cur_prefix, keypart_map, + HA_READ_AFTER_KEY); + if (result || last_range->max_keypart_map == 0) { + /* + Only return if actual failure occurred. For HA_ERR_KEY_NOT_FOUND + or HA_ERR_END_OF_FILE, we just want to continue to reach the next + set of ranges. It is possible for the storage engine to return + HA_ERR_KEY_NOT_FOUND/HA_ERR_END_OF_FILE even when there are more + keys if it respects the end range set by the read_range_first call + below. + */ + if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + } else { + /* + For storage engines that don't respect end range, check if we've + moved past the current range. + */ + key_range previous_endpoint; + last_range->make_max_endpoint(&previous_endpoint, prefix_length, + keypart_map); + if (file->compare_key(&previous_endpoint) <= 0) + DBUG_RETURN(0); + } + } + + uint count= ranges.elements - (uint)(cur_range - (QUICK_RANGE**) ranges.buffer); + if (count == 0) + { + /* Ranges have already been used up before. None is left for read. */ + last_range= 0; + DBUG_RETURN(HA_ERR_END_OF_FILE); + } + last_range= *(cur_range++); + + key_range start_key, end_key; + last_range->make_min_endpoint(&start_key, prefix_length, keypart_map); + last_range->make_max_endpoint(&end_key, prefix_length, keypart_map); + + result= file->read_range_first(last_range->min_keypart_map ? &start_key : 0, + last_range->max_keypart_map ? &end_key : 0, + MY_TEST(last_range->flag & EQ_RANGE), + TRUE); + if (last_range->flag == (UNIQUE_RANGE | EQ_RANGE)) + last_range= 0; // Stop searching + + if (result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + last_range= 0; // No matching rows; go to next range + } +} + + +/* Get next for geometrical indexes */ + +int QUICK_RANGE_SELECT_GEOM::get_next() +{ + DBUG_ENTER("QUICK_RANGE_SELECT_GEOM::get_next"); + + for (;;) + { + int result; + if (last_range) + { + // Already read through key + result= file->ha_index_next_same(record, last_range->min_key, + last_range->min_length); + if (result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + } + + uint count= ranges.elements - (uint)(cur_range - (QUICK_RANGE**) ranges.buffer); + if (count == 0) + { + /* Ranges have already been used up before. None is left for read. */ + last_range= 0; + DBUG_RETURN(HA_ERR_END_OF_FILE); + } + last_range= *(cur_range++); + + result= file->ha_index_read_map(record, last_range->min_key, + last_range->min_keypart_map, + (ha_rkey_function)(last_range->flag ^ + GEOM_FLAG)); + if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + last_range= 0; // Not found, to next range + } +} + + +/* + Check if current row will be retrieved by this QUICK_RANGE_SELECT + + NOTES + It is assumed that currently a scan is being done on another index + which reads all necessary parts of the index that is scanned by this + quick select. + The implementation does a binary search on sorted array of disjoint + ranges, without taking size of range into account. + + This function is used to filter out clustered PK scan rows in + index_merge quick select. + + RETURN + TRUE if current row will be retrieved by this quick select + FALSE if not +*/ + +bool QUICK_RANGE_SELECT::row_in_ranges() +{ + QUICK_RANGE *res; + uint min= 0; + uint max= ranges.elements - 1; + uint mid= (max + min)/2; + + while (min != max) + { + if (cmp_next(*(QUICK_RANGE**)dynamic_array_ptr(&ranges, mid))) + { + /* current row value > mid->max */ + min= mid + 1; + } + else + max= mid; + mid= (min + max) / 2; + } + res= *(QUICK_RANGE**)dynamic_array_ptr(&ranges, mid); + return (!cmp_next(res) && !cmp_prev(res)); +} + +/* + This is a hack: we inherit from QUICK_RANGE_SELECT so that we can use the + get_next() interface, but we have to hold a pointer to the original + QUICK_RANGE_SELECT because its data are used all over the place. What + should be done is to factor out the data that is needed into a base + class (QUICK_SELECT), and then have two subclasses (_ASC and _DESC) + which handle the ranges and implement the get_next() function. But + for now, this seems to work right at least. + */ + +QUICK_SELECT_DESC::QUICK_SELECT_DESC(QUICK_RANGE_SELECT *q, + uint used_key_parts_arg) + :QUICK_RANGE_SELECT(*q), rev_it(rev_ranges), + used_key_parts (used_key_parts_arg) +{ + QUICK_RANGE *r; + /* + Use default MRR implementation for reverse scans. No table engine + currently can do an MRR scan with output in reverse index order. + */ + mrr_buf_desc= NULL; + mrr_flags |= HA_MRR_USE_DEFAULT_IMPL; + mrr_buf_size= 0; + + QUICK_RANGE **pr= (QUICK_RANGE**)ranges.buffer; + QUICK_RANGE **end_range= pr + ranges.elements; + for (; pr!=end_range; pr++) + rev_ranges.push_front(*pr); + + /* Remove EQ_RANGE flag for keys that are not using the full key */ + for (r = rev_it++; r; r = rev_it++) + { + if ((r->flag & EQ_RANGE) && + head->key_info[index].key_length != r->max_length) + r->flag&= ~EQ_RANGE; + } + rev_it.rewind(); + q->dont_free=1; // Don't free shared mem +} + + +int QUICK_SELECT_DESC::get_next() +{ + DBUG_ENTER("QUICK_SELECT_DESC::get_next"); + + /* The max key is handled as follows: + * - if there is NO_MAX_RANGE, start at the end and move backwards + * - if it is an EQ_RANGE, which means that max key covers the entire + * key, go directly to the key and read through it (sorting backwards is + * same as sorting forwards) + * - if it is NEAR_MAX, go to the key or next, step back once, and + * move backwards + * - otherwise (not NEAR_MAX == include the key), go after the key, + * step back once, and move backwards + */ + + for (;;) + { + int result; + if (last_range) + { // Already read through key + result = ((last_range->flag & EQ_RANGE && + used_key_parts <= head->key_info[index].user_defined_key_parts) ? + file->ha_index_next_same(record, last_range->min_key, + last_range->min_length) : + file->ha_index_prev(record)); + if (!result) + { + if (cmp_prev(*rev_it.ref()) == 0) + DBUG_RETURN(0); + } + else if (result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + } + + if (!(last_range= rev_it++)) + DBUG_RETURN(HA_ERR_END_OF_FILE); // All ranges used + + key_range start_key; + start_key.key= (const uchar*) last_range->min_key; + start_key.length= last_range->min_length; + start_key.flag= ((last_range->flag & NEAR_MIN) ? HA_READ_AFTER_KEY : + (last_range->flag & EQ_RANGE) ? + HA_READ_KEY_EXACT : HA_READ_KEY_OR_NEXT); + start_key.keypart_map= last_range->min_keypart_map; + key_range end_key; + end_key.key= (const uchar*) last_range->max_key; + end_key.length= last_range->max_length; + end_key.flag= (last_range->flag & NEAR_MAX ? HA_READ_BEFORE_KEY : + HA_READ_AFTER_KEY); + end_key.keypart_map= last_range->max_keypart_map; + result= file->prepare_range_scan((last_range->flag & NO_MIN_RANGE) ? NULL : &start_key, + (last_range->flag & NO_MAX_RANGE) ? NULL : &end_key); + if (result) + { + DBUG_RETURN(result); + } + + if (last_range->flag & NO_MAX_RANGE) // Read last record + { + int local_error; + if (unlikely((local_error= file->ha_index_last(record)))) + DBUG_RETURN(local_error); // Empty table + if (cmp_prev(last_range) == 0) + DBUG_RETURN(0); + last_range= 0; // No match; go to next range + continue; + } + + if (last_range->flag & EQ_RANGE && + used_key_parts <= head->key_info[index].user_defined_key_parts) + + { + result= file->ha_index_read_map(record, last_range->max_key, + last_range->max_keypart_map, + HA_READ_KEY_EXACT); + } + else + { + DBUG_ASSERT(last_range->flag & NEAR_MAX || + (last_range->flag & EQ_RANGE && + used_key_parts > head->key_info[index].user_defined_key_parts) || + range_reads_after_key(last_range)); + result= file->ha_index_read_map(record, last_range->max_key, + last_range->max_keypart_map, + ((last_range->flag & NEAR_MAX) ? + HA_READ_BEFORE_KEY : + HA_READ_PREFIX_LAST_OR_PREV)); + } + if (result) + { + if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE) + DBUG_RETURN(result); + last_range= 0; // Not found, to next range + continue; + } + if (cmp_prev(last_range) == 0) + { + if (last_range->flag == (UNIQUE_RANGE | EQ_RANGE)) + last_range= 0; // Stop searching + DBUG_RETURN(0); // Found key is in range + } + last_range= 0; // To next range + } +} + + +/** + Create a compatible quick select with the result ordered in an opposite way + + @param used_key_parts_arg Number of used key parts + + @retval NULL in case of errors (OOM etc) + @retval pointer to a newly created QUICK_SELECT_DESC if success +*/ + +QUICK_SELECT_I *QUICK_RANGE_SELECT::make_reverse(uint used_key_parts_arg) +{ + QUICK_SELECT_DESC *new_quick= new QUICK_SELECT_DESC(this, used_key_parts_arg); + if (new_quick == NULL) + { + delete new_quick; + return NULL; + } + return new_quick; +} + + +/* + Compare if found key is over max-value + Returns 0 if key <= range->max_key + TODO: Figure out why can't this function be as simple as cmp_prev(). +*/ + +int QUICK_RANGE_SELECT::cmp_next(QUICK_RANGE *range_arg) +{ + if (range_arg->flag & NO_MAX_RANGE) + return 0; /* key can't be to large */ + + KEY_PART *key_part=key_parts; + uint store_length; + + for (uchar *key=range_arg->max_key, *end=key+range_arg->max_length; + key < end; + key+= store_length, key_part++) + { + int cmp; + store_length= key_part->store_length; + if (key_part->null_bit) + { + if (*key) + { + if (!key_part->field->is_null()) + return 1; + continue; + } + else if (key_part->field->is_null()) + return 0; + key++; // Skip null byte + store_length--; + } + if ((cmp=key_part->field->key_cmp(key, key_part->length)) < 0) + return 0; + if (cmp > 0) + return 1; + } + return (range_arg->flag & NEAR_MAX) ? 1 : 0; // Exact match +} + + +/* + Returns 0 if found key is inside range (found key >= range->min_key). +*/ + +int QUICK_RANGE_SELECT::cmp_prev(QUICK_RANGE *range_arg) +{ + int cmp; + if (range_arg->flag & NO_MIN_RANGE) + return 0; /* key can't be to small */ + + cmp= key_cmp(key_part_info, range_arg->min_key, + range_arg->min_length); + if (cmp > 0 || (cmp == 0 && !(range_arg->flag & NEAR_MIN))) + return 0; + return 1; // outside of range +} + + +/* + * TRUE if this range will require using HA_READ_AFTER_KEY + See comment in get_next() about this + */ + +bool QUICK_SELECT_DESC::range_reads_after_key(QUICK_RANGE *range_arg) +{ + return ((range_arg->flag & (NO_MAX_RANGE | NEAR_MAX)) || + !(range_arg->flag & EQ_RANGE) || + head->key_info[index].key_length != range_arg->max_length) ? 1 : 0; +} + + +void QUICK_SELECT_I::add_key_name(String *str, bool *first) +{ + KEY *key_info= head->key_info + index; + + if (*first) + *first= FALSE; + else + str->append(','); + str->append(&key_info->name); +} + + +Explain_quick_select* QUICK_RANGE_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + if ((res= new (local_alloc) Explain_quick_select(QS_TYPE_RANGE))) + res->range.set(local_alloc, &head->key_info[index], max_used_key_length); + return res; +} + + +Explain_quick_select* +QUICK_GROUP_MIN_MAX_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + if ((res= new (local_alloc) Explain_quick_select(QS_TYPE_GROUP_MIN_MAX))) + res->range.set(local_alloc, &head->key_info[index], max_used_key_length); + return res; +} + + +Explain_quick_select* +QUICK_INDEX_SORT_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + if (!(res= new (local_alloc) Explain_quick_select(get_type()))) + return NULL; + + QUICK_RANGE_SELECT *quick; + Explain_quick_select *child_explain; + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + while ((quick= it++)) + { + if ((child_explain= quick->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + + if (pk_quick_select) + { + if ((child_explain= pk_quick_select->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + return res; +} + + +/* + Same as QUICK_INDEX_SORT_SELECT::get_explain(), but primary key is printed + first +*/ + +Explain_quick_select* +QUICK_INDEX_INTERSECT_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + Explain_quick_select *child_explain; + + if (!(res= new (local_alloc) Explain_quick_select(get_type()))) + return NULL; + + if (pk_quick_select) + { + if ((child_explain= pk_quick_select->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + + QUICK_RANGE_SELECT *quick; + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + while ((quick= it++)) + { + if ((child_explain= quick->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + return res; +} + + +Explain_quick_select* +QUICK_ROR_INTERSECT_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + Explain_quick_select *child_explain; + + if (!(res= new (local_alloc) Explain_quick_select(get_type()))) + return NULL; + + QUICK_SELECT_WITH_RECORD *qr; + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + while ((qr= it++)) + { + if ((child_explain= qr->quick->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + + if (cpk_quick) + { + if ((child_explain= cpk_quick->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + return res; +} + + +Explain_quick_select* +QUICK_ROR_UNION_SELECT::get_explain(MEM_ROOT *local_alloc) +{ + Explain_quick_select *res; + Explain_quick_select *child_explain; + + if (!(res= new (local_alloc) Explain_quick_select(get_type()))) + return NULL; + + QUICK_SELECT_I *quick; + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + while ((quick= it++)) + { + if ((child_explain= quick->get_explain(local_alloc))) + res->children.push_back(child_explain); + else + return NULL; + } + + return res; +} + + +void QUICK_SELECT_I::add_key_and_length(String *key_names, + String *used_lengths, + bool *first) +{ + char buf[64]; + size_t length; + KEY *key_info= head->key_info + index; + + if (*first) + *first= FALSE; + else + { + key_names->append(','); + used_lengths->append(','); + } + key_names->append(&key_info->name); + length= longlong10_to_str(max_used_key_length, buf, 10) - buf; + used_lengths->append(buf, length); +} + + +void QUICK_RANGE_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + bool first= TRUE; + + add_key_and_length(key_names, used_lengths, &first); +} + +void QUICK_INDEX_MERGE_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + QUICK_RANGE_SELECT *quick; + bool first= TRUE; + + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + + while ((quick= it++)) + { + quick->add_key_and_length(key_names, used_lengths, &first); + } + + if (pk_quick_select) + pk_quick_select->add_key_and_length(key_names, used_lengths, &first); +} + + +void QUICK_INDEX_INTERSECT_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + QUICK_RANGE_SELECT *quick; + bool first= TRUE; + + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + + if (pk_quick_select) + pk_quick_select->add_key_and_length(key_names, used_lengths, &first); + + while ((quick= it++)) + { + quick->add_key_and_length(key_names, used_lengths, &first); + } +} + +void QUICK_ROR_INTERSECT_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + QUICK_SELECT_WITH_RECORD *qr; + bool first= TRUE; + + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + + while ((qr= it++)) + { + qr->quick->add_key_and_length(key_names, used_lengths, &first); + } + if (cpk_quick) + cpk_quick->add_key_and_length(key_names, used_lengths, &first); +} + +void QUICK_ROR_UNION_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + QUICK_SELECT_I *quick; + bool first= TRUE; + + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + + while ((quick= it++)) + { + if (first) + first= FALSE; + else + { + used_lengths->append(','); + key_names->append(','); + } + quick->add_keys_and_lengths(key_names, used_lengths); + } +} + + +void QUICK_RANGE_SELECT::add_used_key_part_to_set() +{ + uint key_len; + KEY_PART *part= key_parts; + for (key_len=0; key_len < max_used_key_length; + key_len += (part++)->store_length) + { + /* + We have to use field_index instead of part->field + as for partial fields, part->field points to + a temporary field that is only part of the original + field. field_index always points to the original field + */ + Field *field= head->field[part->field->field_index]; + field->register_field_in_read_map(); + } +} + + +void QUICK_GROUP_MIN_MAX_SELECT::add_used_key_part_to_set() +{ + uint key_len; + KEY_PART_INFO *part= index_info->key_part; + for (key_len=0; key_len < max_used_key_length; + key_len += (part++)->store_length) + { + /* + We have to use field_index instead of part->field + as for partial fields, part->field points to + a temporary field that is only part of the original + field. field_index always points to the original field + */ + Field *field= head->field[part->field->field_index]; + field->register_field_in_read_map(); + } +} + + +void QUICK_ROR_INTERSECT_SELECT::add_used_key_part_to_set() +{ + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + QUICK_SELECT_WITH_RECORD *quick; + while ((quick= it++)) + { + quick->quick->add_used_key_part_to_set(); + } +} + + +void QUICK_INDEX_SORT_SELECT::add_used_key_part_to_set() +{ + QUICK_RANGE_SELECT *quick; + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + while ((quick= it++)) + { + quick->add_used_key_part_to_set(); + } + if (pk_quick_select) + pk_quick_select->add_used_key_part_to_set(); +} + + +void QUICK_ROR_UNION_SELECT::add_used_key_part_to_set() +{ + QUICK_SELECT_I *quick; + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + + while ((quick= it++)) + { + quick->add_used_key_part_to_set(); + } +} + + +/******************************************************************************* +* Implementation of QUICK_GROUP_MIN_MAX_SELECT +*******************************************************************************/ + +static inline uint get_field_keypart(KEY *index, Field *field); +static bool get_sel_arg_for_keypart(Field *field, SEL_ARG *index_range_tree, + SEL_ARG **cur_range); +static bool get_constant_key_infix(KEY *index_info, SEL_ARG *index_range_tree, + KEY_PART_INFO *first_non_group_part, + KEY_PART_INFO *min_max_arg_part, + KEY_PART_INFO *last_part, THD *thd, + uchar *key_infix, uint *key_infix_len, + KEY_PART_INFO **first_non_infix_part); +static bool +check_group_min_max_predicates(Item *cond, Item_field *min_max_arg_item, + Field::imagetype image_type, + bool *has_min_max_fld, bool *has_other_fld); + +static void +cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts, + uint group_key_parts, SEL_TREE *range_tree, + SEL_ARG *index_tree, ha_rows quick_prefix_records, + bool have_min, bool have_max, + double *read_cost, ha_rows *records); + + +/** + Test if this access method is applicable to a GROUP query with MIN/MAX + functions, and if so, construct a new TRP object. + + DESCRIPTION + Test whether a query can be computed via a QUICK_GROUP_MIN_MAX_SELECT. + Queries computable via a QUICK_GROUP_MIN_MAX_SELECT must satisfy the + following conditions: + A) Table T has at least one compound index I of the form: + I = <A_1, ...,A_k, [B_1,..., B_m], C, [D_1,...,D_n]> + B) Query conditions: + B0. Q is over a single table T. + B1. The attributes referenced by Q are a subset of the attributes of I. + B2. All attributes QA in Q can be divided into 3 overlapping groups: + - SA = {S_1, ..., S_l, [C]} - from the SELECT clause, where C is + referenced by any number of MIN and/or MAX functions if present. + - WA = {W_1, ..., W_p} - from the WHERE clause + - GA = <G_1, ..., G_k> - from the GROUP BY clause (if any) + = SA - if Q is a DISTINCT query (based on the + equivalence of DISTINCT and GROUP queries. + - NGA = QA - (GA union C) = {NG_1, ..., NG_m} - the ones not in + GROUP BY and not referenced by MIN/MAX functions. + with the following properties specified below. + B3. If Q has a GROUP BY WITH ROLLUP clause the access method is not + applicable. + + SA1. There is at most one attribute in SA referenced by any number of + MIN and/or MAX functions which, which if present, is denoted as C. + SA2. The position of the C attribute in the index is after the last A_k. + SA3. The attribute C can be referenced in the WHERE clause only in + predicates of the forms: + - (C {< | <= | > | >= | =} const) + - (const {< | <= | > | >= | =} C) + - (C between const_i and const_j) + - C IS NULL + - C IS NOT NULL + - C != const + SA4. If Q has a GROUP BY clause, there are no other aggregate functions + except MIN and MAX. For queries with DISTINCT, aggregate functions + are allowed. + SA5. The select list in DISTINCT queries should not contain expressions. + SA6. Clustered index can not be used by GROUP_MIN_MAX quick select + for AGG_FUNC(DISTINCT ...) optimization because cursor position is + never stored after a unique key lookup in the clustered index and + furhter index_next/prev calls can not be used. So loose index scan + optimization can not be used in this case. + SA7. If Q has both AGG_FUNC(DISTINCT ...) and MIN/MAX() functions then this + access method is not used. + For above queries MIN/MAX() aggregation has to be done at + nested_loops_join (end_send_group). But with current design MIN/MAX() + is always set as part of loose index scan. Because of this mismatch + MIN() and MAX() values will be set incorrectly. For such queries to + work we need a new interface for loose index scan. This new interface + should only fetch records with min and max values and let + end_send_group to do aggregation. Until then do not use + loose_index_scan. + GA1. If Q has a GROUP BY clause, then GA is a prefix of I. That is, if + G_i = A_j => i = j. + GA2. If Q has a DISTINCT clause, then there is a permutation of SA that + forms a prefix of I. This permutation is used as the GROUP clause + when the DISTINCT query is converted to a GROUP query. + GA3. The attributes in GA may participate in arbitrary predicates, divided + into two groups: + - RNG(G_1,...,G_q ; where q <= k) is a range condition over the + attributes of a prefix of GA + - PA(G_i1,...G_iq) is an arbitrary predicate over an arbitrary subset + of GA. Since P is applied to only GROUP attributes it filters some + groups, and thus can be applied after the grouping. + GA4. There are no expressions among G_i, just direct column references. + NGA1.If in the index I there is a gap between the last GROUP attribute G_k, + and the MIN/MAX attribute C, then NGA must consist of exactly the + index attributes that constitute the gap. As a result there is a + permutation of NGA, BA=<B_1,...,B_m>, that coincides with the gap + in the index. + NGA2.If BA <> {}, then the WHERE clause must contain a conjunction EQ of + equality conditions for all NG_i of the form (NG_i = const) or + (const = NG_i), such that each NG_i is referenced in exactly one + conjunct. Informally, the predicates provide constants to fill the + gap in the index. + NGA3.If BA <> {}, there can only be one range. TODO: This is a code + limitation and is not strictly needed. See BUG#15947433 + WA1. There are no other attributes in the WHERE clause except the ones + referenced in predicates RNG, PA, PC, EQ defined above. Therefore + WA is subset of (GA union NGA union C) for GA,NGA,C that pass the + above tests. By transitivity then it also follows that each WA_i + participates in the index I (if this was already tested for GA, NGA + and C). + WA2. If there is a predicate on C, then it must be in conjunction + to all predicates on all earlier keyparts in I. + + C) Overall query form: + SELECT EXPR([A_1,...,A_k], [B_1,...,B_m], [MIN(C)], [MAX(C)]) + FROM T + WHERE [RNG(A_1,...,A_p ; where p <= k)] + [AND EQ(B_1,...,B_m)] + [AND PC(C)] + [AND PA(A_i1,...,A_iq)] + GROUP BY A_1,...,A_k + [HAVING PH(A_1, ..., B_1,..., C)] + where EXPR(...) is an arbitrary expression over some or all SELECT fields, + or: + SELECT DISTINCT A_i1,...,A_ik + FROM T + WHERE [RNG(A_1,...,A_p ; where p <= k)] + [AND PA(A_i1,...,A_iq)]; + + NOTES + If the current query satisfies the conditions above, and if + (mem_root! = NULL), then the function constructs and returns a new TRP + object, that is later used to construct a new QUICK_GROUP_MIN_MAX_SELECT. + If (mem_root == NULL), then the function only tests whether the current + query satisfies the conditions above, and, if so, sets + is_applicable = TRUE. + + Queries with DISTINCT for which index access can be used are transformed + into equivalent group-by queries of the form: + + SELECT A_1,...,A_k FROM T + WHERE [RNG(A_1,...,A_p ; where p <= k)] + [AND PA(A_i1,...,A_iq)] + GROUP BY A_1,...,A_k; + + The group-by list is a permutation of the select attributes, according + to their order in the index. + + TODO + - What happens if the query groups by the MIN/MAX field, and there is no + other field as in: "select MY_MIN(a) from t1 group by a" ? + - We assume that the general correctness of the GROUP-BY query was checked + before this point. Is this correct, or do we have to check it completely? + - Lift the limitation in condition (B3), that is, make this access method + applicable to ROLLUP queries. + + @param param Parameter from test_quick_select + @param sel_tree Range tree generated by get_mm_tree + @param read_time Best read time so far of table or index scan time + @return table read plan + @retval NULL Loose index scan not applicable or mem_root == NULL + @retval !NULL Loose index scan table read plan +*/ + +static TRP_GROUP_MIN_MAX * +get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time) +{ + THD *thd= param->thd; + JOIN *join= thd->lex->current_select->join; + TABLE *table= param->table; + bool have_min= FALSE; /* TRUE if there is a MIN function. */ + bool have_max= FALSE; /* TRUE if there is a MAX function. */ + Item_field *min_max_arg_item= NULL; // The argument of all MIN/MAX functions + KEY_PART_INFO *min_max_arg_part= NULL; /* The corresponding keypart. */ + uint group_prefix_len= 0; /* Length (in bytes) of the key prefix. */ + KEY *index_info= NULL; /* The index chosen for data access. */ + uint index= 0; /* The id of the chosen index. */ + uint group_key_parts= 0; // Number of index key parts in the group prefix. + uint used_key_parts= 0; /* Number of index key parts used for access. */ + uchar key_infix[MAX_KEY_LENGTH]; /* Constants from equality predicates.*/ + uint key_infix_len= 0; /* Length of key_infix. */ + TRP_GROUP_MIN_MAX *read_plan= NULL; /* The eventually constructed TRP. */ + uint key_part_nr; + uint elements_in_group; + ORDER *tmp_group; + Item *item; + Item_field *item_field; + bool is_agg_distinct; + List<Item_field> agg_distinct_flds; + DBUG_ENTER("get_best_group_min_max"); + + Json_writer_object trace_group(thd, "group_index_range"); + const char* cause= NULL; + + /* Perform few 'cheap' tests whether this access method is applicable. */ + if (!join) /* This is not a select statement. */ + cause= "no join"; + else if (join->table_count != 1) /* The query must reference one table. */ + cause= "not single_table"; + else if (join->select_lex->olap == ROLLUP_TYPE) /* Check (B3) for ROLLUP */ + cause= "rollup"; + else if (table->s->keys == 0) /* There are no indexes to use. */ + cause= "no index"; + else if (join->conds && join->conds->used_tables() + & OUTER_REF_TABLE_BIT) /* Cannot execute with correlated conditions. */ + cause= "correlated conditions"; + + if (cause) + { + trace_group.add("chosen", false).add("cause", cause); + DBUG_RETURN(NULL); + } + + is_agg_distinct = is_indexed_agg_distinct(join, &agg_distinct_flds); + + if ((!join->group_list) && /* Neither GROUP BY nor a DISTINCT query. */ + (!join->select_distinct) && + !is_agg_distinct) + { + trace_group.add("chosen", false).add("cause","no group by or distinct"); + DBUG_RETURN(NULL); + } + /* Analyze the query in more detail. */ + + /* Check (SA1,SA4) and store the only MIN/MAX argument - the C attribute.*/ + List_iterator<Item> select_items_it(join->fields_list); + + if (join->sum_funcs[0]) + { + Item_sum *min_max_item; + Item_sum **func_ptr= join->sum_funcs; + while ((min_max_item= *(func_ptr++))) + { + if (min_max_item->sum_func() == Item_sum::MIN_FUNC) + have_min= TRUE; + else if (min_max_item->sum_func() == Item_sum::MAX_FUNC) + have_max= TRUE; + else if (is_agg_distinct && + (min_max_item->sum_func() == Item_sum::COUNT_DISTINCT_FUNC || + min_max_item->sum_func() == Item_sum::SUM_DISTINCT_FUNC || + min_max_item->sum_func() == Item_sum::AVG_DISTINCT_FUNC)) + continue; + else + { + trace_group.add("chosen", false) + .add("cause", "not applicable aggregate function"); + DBUG_RETURN(NULL); + } + + /* The argument of MIN/MAX. */ + Item *expr= min_max_item->get_arg(0)->real_item(); + if (expr->type() == Item::FIELD_ITEM) /* Is it an attribute? */ + { + if (! min_max_arg_item) + min_max_arg_item= (Item_field*) expr; + else if (! min_max_arg_item->eq(expr, 1)) + { + trace_group.add("chosen", false) + .add("cause", "arguments different in min max function"); + DBUG_RETURN(NULL); + } + } + else + { + trace_group.add("chosen", false) + .add("cause", "no field item in min max function"); + DBUG_RETURN(NULL); + } + } + } + + /* Check (SA7). */ + if (is_agg_distinct && (have_max || have_min)) + { + trace_group.add("chosen", false) + .add("cause", "have both agg distinct and min max"); + DBUG_RETURN(NULL); + } + + /* Check (SA5). */ + if (join->select_distinct) + { + trace_group.add("distinct_query", true); + while ((item= select_items_it++)) + { + if (item->real_item()->type() != Item::FIELD_ITEM) + { + trace_group.add("chosen", false) + .add("cause", "distinct field is expression"); + DBUG_RETURN(NULL); + } + } + } + + /* Check (GA4) - that there are no expressions among the group attributes. */ + elements_in_group= 0; + for (tmp_group= join->group_list; tmp_group; tmp_group= tmp_group->next) + { + if ((*tmp_group->item)->real_item()->type() != Item::FIELD_ITEM) + { + trace_group.add("chosen", false) + .add("cause", "group field is expression"); + DBUG_RETURN(NULL); + } + elements_in_group++; + } + + /* + Check that table has at least one compound index such that the conditions + (GA1,GA2) are all TRUE. If there is more than one such index, select the + first one. Here we set the variables: group_prefix_len and index_info. + */ + /* Cost-related variables for the best index so far. */ + double best_read_cost= DBL_MAX; + ha_rows best_records= 0; + SEL_ARG *best_index_tree= NULL; + ha_rows best_quick_prefix_records= 0; + uint best_param_idx= 0; + + const uint pk= param->table->s->primary_key; + uint max_key_part; + SEL_ARG *cur_index_tree= NULL; + ha_rows cur_quick_prefix_records= 0; + + // We go through allowed indexes + Json_writer_array trace_indexes(thd, "potential_group_range_indexes"); + + for (uint cur_param_idx= 0; cur_param_idx < param->keys ; ++cur_param_idx) + { + const uint cur_index= param->real_keynr[cur_param_idx]; + KEY *const cur_index_info= &table->key_info[cur_index]; + + Json_writer_object trace_idx(thd); + trace_idx.add("index", cur_index_info->name); + + KEY_PART_INFO *cur_part; + KEY_PART_INFO *end_part; /* Last part for loops. */ + /* Last index part. */ + KEY_PART_INFO *last_part; + KEY_PART_INFO *first_non_group_part; + KEY_PART_INFO *first_non_infix_part; + uint key_parts; + uint key_infix_parts; + uint cur_group_key_parts= 0; + uint cur_group_prefix_len= 0; + double cur_read_cost; + ha_rows cur_records; + key_map used_key_parts_map; + uint cur_key_infix_len= 0; + uchar cur_key_infix[MAX_KEY_LENGTH]; + uint cur_used_key_parts; + + /* + Check (B1) - if current index is covering. + (was also: "Exclude UNIQUE indexes ..." but this was removed because + there are cases Loose Scan over a multi-part index is useful). + */ + if (!table->covering_keys.is_set(cur_index) || + !table->keys_in_use_for_group_by.is_set(cur_index)) + { + cause= "not covering"; + goto next_index; + } + + /* + This function is called on the precondition that the index is covering. + Therefore if the GROUP BY list contains more elements than the index, + these are duplicates. The GROUP BY list cannot be a prefix of the index. + */ + if (elements_in_group > table->actual_n_key_parts(cur_index_info)) + { + cause= "group key parts greater than index key parts"; + goto next_index; + } + + /* + Unless extended keys can be used for cur_index: + If the current storage manager is such that it appends the primary key to + each index, then the above condition is insufficient to check if the + index is covering. In such cases it may happen that some fields are + covered by the PK index, but not by the current index. Since we can't + use the concatenation of both indexes for index lookup, such an index + does not qualify as covering in our case. If this is the case, below + we check that all query fields are indeed covered by 'cur_index'. + */ + if (cur_index_info->user_defined_key_parts == table->actual_n_key_parts(cur_index_info) + && pk < MAX_KEY && cur_index != pk && + (table->file->ha_table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX)) + { + /* For each table field */ + for (uint i= 0; i < table->s->fields; i++) + { + Field *cur_field= table->field[i]; + /* + If the field is used in the current query ensure that it's + part of 'cur_index' + */ + if (bitmap_is_set(table->read_set, cur_field->field_index) && + !cur_field->part_of_key_not_clustered.is_set(cur_index)) + { + cause= "not covering"; + goto next_index; // Field was not part of key + } + } + } + + trace_idx.add("covering", true); + + max_key_part= 0; + used_key_parts_map.clear_all(); + + /* + Check (GA1) for GROUP BY queries. + */ + if (join->group_list) + { + cur_part= cur_index_info->key_part; + end_part= cur_part + table->actual_n_key_parts(cur_index_info); + /* Iterate in parallel over the GROUP list and the index parts. */ + for (tmp_group= join->group_list; tmp_group && (cur_part != end_part); + tmp_group= tmp_group->next, cur_part++) + { + /* + TODO: + tmp_group::item is an array of Item, is it OK to consider only the + first Item? If so, then why? What is the array for? + */ + /* Above we already checked that all group items are fields. */ + DBUG_ASSERT((*tmp_group->item)->real_item()->type() == Item::FIELD_ITEM); + Item_field *group_field= (Item_field *) (*tmp_group->item)->real_item(); + if (group_field->field->eq(cur_part->field)) + { + cur_group_prefix_len+= cur_part->store_length; + ++cur_group_key_parts; + max_key_part= (uint)(cur_part - cur_index_info->key_part) + 1; + used_key_parts_map.set_bit(max_key_part); + } + else + { + cause= "group attribute not prefix in index"; + goto next_index; + } + } + } + /* + Check (GA2) if this is a DISTINCT query. + If GA2, then Store a new ORDER object in group_fields_array at the + position of the key part of item_field->field. Thus we get the ORDER + objects for each field ordered as the corresponding key parts. + Later group_fields_array of ORDER objects is used to convert the query + to a GROUP query. + */ + if ((!join->group && join->select_distinct) || + is_agg_distinct) + { + if (!is_agg_distinct) + { + select_items_it.rewind(); + } + + List_iterator<Item_field> agg_distinct_flds_it (agg_distinct_flds); + while (NULL != (item = (is_agg_distinct ? + (Item *) agg_distinct_flds_it++ : select_items_it++))) + { + /* (SA5) already checked above. */ + item_field= (Item_field*) item->real_item(); + DBUG_ASSERT(item->real_item()->type() == Item::FIELD_ITEM); + + /* not doing loose index scan for derived tables */ + if (!item_field->field) + { + cause= "derived table"; + goto next_index; + } + + /* Find the order of the key part in the index. */ + key_part_nr= get_field_keypart(cur_index_info, item_field->field); + /* + Check if this attribute was already present in the select list. + If it was present, then its corresponding key part was alredy used. + */ + if (used_key_parts_map.is_set(key_part_nr)) + continue; + if (key_part_nr < 1 || + (!is_agg_distinct && key_part_nr > join->fields_list.elements)) + { + cause= "select attribute not prefix in index"; + goto next_index; + } + cur_part= cur_index_info->key_part + key_part_nr - 1; + cur_group_prefix_len+= cur_part->store_length; + used_key_parts_map.set_bit(key_part_nr); + ++cur_group_key_parts; + max_key_part= MY_MAX(max_key_part,key_part_nr); + } + /* + Check that used key parts forms a prefix of the index. + To check this we compare bits in all_parts and cur_parts. + all_parts have all bits set from 0 to (max_key_part-1). + cur_parts have bits set for only used keyparts. + */ + ulonglong all_parts, cur_parts; + all_parts= (1ULL << max_key_part) - 1; + cur_parts= used_key_parts_map.to_ulonglong() >> 1; + if (all_parts != cur_parts) + goto next_index; + } + + /* Check (SA2). */ + if (min_max_arg_item) + { + key_part_nr= get_field_keypart(cur_index_info, min_max_arg_item->field); + if (key_part_nr <= cur_group_key_parts) + { + cause= "aggregate column not suffix in idx"; + goto next_index; + } + min_max_arg_part= cur_index_info->key_part + key_part_nr - 1; + } + + /* + Aplly a heuristic: there is no point to use loose index scan when we're + using the whole unique index. + */ + if (cur_index_info->flags & HA_NOSAME && + cur_group_key_parts == cur_index_info->user_defined_key_parts) + { + cause= "using unique index"; + goto next_index; + } + + /* + Check (NGA1, NGA2) and extract a sequence of constants to be used as part + of all search keys. + */ + + /* + If there is MIN/MAX, each keypart between the last group part and the + MIN/MAX part must participate in one equality with constants, and all + keyparts after the MIN/MAX part must not be referenced in the query. + + If there is no MIN/MAX, the keyparts after the last group part can be + referenced only in equalities with constants, and the referenced keyparts + must form a sequence without any gaps that starts immediately after the + last group keypart. + */ + key_parts= table->actual_n_key_parts(cur_index_info); + last_part= cur_index_info->key_part + key_parts; + first_non_group_part= (cur_group_key_parts < key_parts) ? + cur_index_info->key_part + cur_group_key_parts : + NULL; + first_non_infix_part= min_max_arg_part ? + (min_max_arg_part < last_part) ? + min_max_arg_part : + NULL : + NULL; + if (first_non_group_part && + (!min_max_arg_part || (min_max_arg_part - first_non_group_part > 0))) + { + if (tree) + { + SEL_ARG *index_range_tree= tree->keys[cur_param_idx]; + if (!get_constant_key_infix(cur_index_info, index_range_tree, + first_non_group_part, min_max_arg_part, + last_part, thd, cur_key_infix, + &cur_key_infix_len, + &first_non_infix_part)) + { + cause= "nonconst equality gap attribute"; + goto next_index; + } + } + else if (min_max_arg_part && + (min_max_arg_part - first_non_group_part > 0)) + { + /* + There is a gap but no range tree, thus no predicates at all for the + non-group keyparts. + */ + cause= "no nongroup keypart predicate"; + goto next_index; + } + else if (first_non_group_part && join->conds) + { + /* + If there is no MIN/MAX function in the query, but some index + key part is referenced in the WHERE clause, then this index + cannot be used because the WHERE condition over the keypart's + field cannot be 'pushed' to the index (because there is no + range 'tree'), and the WHERE clause must be evaluated before + GROUP BY/DISTINCT. + */ + /* + Store the first and last keyparts that need to be analyzed + into one array that can be passed as parameter. + */ + KEY_PART_INFO *key_part_range[2]; + key_part_range[0]= first_non_group_part; + key_part_range[1]= last_part; + + /* Check if cur_part is referenced in the WHERE clause. */ + if (join->conds->walk(&Item::find_item_in_field_list_processor, 0, + key_part_range)) + { + cause= "keypart reference from where clause"; + goto next_index; + } + } + } + + /* + Test (WA1) partially - that no other keypart after the last infix part is + referenced in the query. + */ + if (first_non_infix_part) + { + cur_part= first_non_infix_part + + (min_max_arg_part && (min_max_arg_part < last_part)); + for (; cur_part != last_part; cur_part++) + { + if (bitmap_is_set(table->read_set, cur_part->field->field_index)) + { + cause= "keypart after infix in query"; + goto next_index; + } + } + } + + /** + Test WA2:If there are conditions on a column C participating in + MIN/MAX, those conditions must be conjunctions to all earlier + keyparts. Otherwise, Loose Index Scan cannot be used. + */ + if (tree && min_max_arg_item) + { + SEL_ARG *index_range_tree= tree->keys[cur_param_idx]; + SEL_ARG *cur_range= NULL; + if (get_sel_arg_for_keypart(min_max_arg_part->field, + index_range_tree, &cur_range) || + (cur_range && cur_range->type != SEL_ARG::KEY_RANGE)) + { + cause= "minmax keypart in disjunctive query"; + goto next_index; + } + } + + /* If we got to this point, cur_index_info passes the test. */ + key_infix_parts= cur_key_infix_len ? (uint) + (first_non_infix_part - first_non_group_part) : 0; + cur_used_key_parts= cur_group_key_parts + key_infix_parts; + + /* Compute the cost of using this index. */ + if (tree) + { + if ((cur_index_tree= tree->keys[cur_param_idx])) + { + cur_quick_prefix_records= param->quick_rows[cur_index]; + if (unlikely(cur_index_tree && thd->trace_started())) + { + Json_writer_array trace_range(thd, "ranges"); + trace_ranges(&trace_range, param, cur_param_idx, + cur_index_tree, cur_index_info->key_part); + } + } + else + cur_quick_prefix_records= HA_POS_ERROR; + } + cost_group_min_max(table, cur_index_info, cur_used_key_parts, + cur_group_key_parts, tree, cur_index_tree, + cur_quick_prefix_records, have_min, have_max, + &cur_read_cost, &cur_records); + /* + If cur_read_cost is lower than best_read_cost use cur_index. + Do not compare doubles directly because they may have different + representations (64 vs. 80 bits). + */ + trace_idx.add("rows", cur_records).add("cost", cur_read_cost); + + if (cur_read_cost < best_read_cost - (DBL_EPSILON * cur_read_cost)) + { + index_info= cur_index_info; + index= cur_index; + best_read_cost= cur_read_cost; + best_records= cur_records; + best_index_tree= cur_index_tree; + best_quick_prefix_records= cur_quick_prefix_records; + best_param_idx= cur_param_idx; + group_key_parts= cur_group_key_parts; + group_prefix_len= cur_group_prefix_len; + key_infix_len= cur_key_infix_len; + if (key_infix_len) + memcpy (key_infix, cur_key_infix, sizeof (key_infix)); + used_key_parts= cur_used_key_parts; + } + + next_index: + if (cause) + { + trace_idx.add("usable", false).add("cause", cause); + cause= NULL; + } + } + + trace_indexes.end(); + + if (!index_info) /* No usable index found. */ + DBUG_RETURN(NULL); + + /* Check (SA3) for the where clause. */ + bool has_min_max_fld= false, has_other_fld= false; + if (join->conds && min_max_arg_item && + !check_group_min_max_predicates(join->conds, min_max_arg_item, + (index_info->flags & HA_SPATIAL) ? + Field::itMBR : Field::itRAW, + &has_min_max_fld, &has_other_fld)) + { + trace_group.add("usable", false) + .add("cause", "unsupported predicate on agg attribute"); + DBUG_RETURN(NULL); + } + + /* + Check (SA6) if clustered key is used + */ + if (is_agg_distinct && table->file->is_clustering_key(index)) + { + trace_group.add("usable", false) + .add("cause", "index is clustered"); + DBUG_RETURN(NULL); + } + + /* The query passes all tests, so construct a new TRP object. */ + read_plan= new (param->mem_root) + TRP_GROUP_MIN_MAX(have_min, have_max, is_agg_distinct, + min_max_arg_part, + group_prefix_len, used_key_parts, + group_key_parts, index_info, index, + key_infix_len, + (key_infix_len > 0) ? key_infix : NULL, + tree, best_index_tree, best_param_idx, + best_quick_prefix_records); + if (read_plan) + { + if (tree && read_plan->quick_prefix_records == 0) + DBUG_RETURN(NULL); + + read_plan->read_cost= best_read_cost; + read_plan->records= best_records; + if (read_time < best_read_cost && is_agg_distinct) + { + trace_group.add("index_scan", true); + read_plan->read_cost= 0; + read_plan->use_index_scan(); + } + + DBUG_PRINT("info", + ("Returning group min/max plan: cost: %g, records: %lu", + read_plan->read_cost, (ulong) read_plan->records)); + } + + DBUG_RETURN(read_plan); +} + + +/* + Check that the MIN/MAX attribute participates only in range predicates + with constants. + + SYNOPSIS + check_group_min_max_predicates() + cond [in] the expression tree being analyzed + min_max_arg [in] the field referenced by the MIN/MAX function(s) + image_type [in] + has_min_max_arg [out] true if the subtree being analyzed references + min_max_arg + has_other_arg [out] true if the subtree being analyzed references a + column other min_max_arg + + DESCRIPTION + The function walks recursively over the cond tree representing a WHERE + clause, and checks condition (SA3) - if a field is referenced by a MIN/MAX + aggregate function, it is referenced only by one of the following + predicates $FUNC$: + {=, !=, <, <=, >, >=, between, is [not] null, multiple equal}. + In addition the function checks that the WHERE condition is equivalent to + "cond1 AND cond2" where : + cond1 - does not use min_max_column at all. + cond2 - is an AND/OR tree with leaves in form + "$FUNC$(min_max_column[, const])". + + RETURN + TRUE if cond passes the test + FALSE o/w +*/ + +static bool +check_group_min_max_predicates(Item *cond, Item_field *min_max_arg_item, + Field::imagetype image_type, + bool *has_min_max_arg, bool *has_other_arg) +{ + DBUG_ENTER("check_group_min_max_predicates"); + DBUG_ASSERT(cond && min_max_arg_item); + + cond= cond->real_item(); + Item::Type cond_type= cond->real_type(); + if (cond_type == Item::COND_ITEM) /* 'AND' or 'OR' */ + { + DBUG_PRINT("info", ("Analyzing: %s", ((Item_func*) cond)->func_name())); + List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list()); + Item *and_or_arg; + Item_func::Functype func_type= ((Item_cond*) cond)->functype(); + bool has_min_max= false, has_other= false; + while ((and_or_arg= li++)) + { + /* + The WHERE clause doesn't pass the condition if: + (1) any subtree doesn't pass the condition or + (2) the subtree passes the test, but it is an OR and it references both + the min/max argument and other columns. + */ + if (!check_group_min_max_predicates(and_or_arg, min_max_arg_item, //1 + image_type, + &has_min_max, &has_other) || + (func_type == Item_func::COND_OR_FUNC && has_min_max && has_other))//2 + DBUG_RETURN(FALSE); + } + *has_min_max_arg= has_min_max || *has_min_max_arg; + *has_other_arg= has_other || *has_other_arg; + DBUG_RETURN(TRUE); + } + + /* + Disallow loose index scan if the MIN/MAX argument field is referenced by + a subquery in the WHERE clause. + */ + + if (unlikely(cond_type == Item::SUBSELECT_ITEM)) + { + Item_subselect *subs_cond= (Item_subselect*) cond; + if (subs_cond->is_correlated) + { + DBUG_ASSERT(subs_cond->upper_refs.elements > 0); + List_iterator_fast<Item_subselect::Ref_to_outside> + li(subs_cond->upper_refs); + Item_subselect::Ref_to_outside *dep; + while ((dep= li++)) + { + if (dep->item->eq(min_max_arg_item, FALSE)) + DBUG_RETURN(FALSE); + } + } + DBUG_RETURN(TRUE); + } + /* + Subquery with IS [NOT] NULL + TODO: Look into the cache_item and optimize it like we do for + subselect's above + */ + if (unlikely(cond_type == Item::CACHE_ITEM)) + DBUG_RETURN(cond->const_item()); + + /* + Condition of the form 'field' is equivalent to 'field <> 0' and thus + satisfies the SA3 condition. + */ + if (cond_type == Item::FIELD_ITEM) + { + DBUG_PRINT("info", ("Analyzing: %s", cond->full_name())); + if (min_max_arg_item->eq((Item_field*)cond, 1)) + *has_min_max_arg= true; + else + *has_other_arg= true; + DBUG_RETURN(TRUE); + } + + /* We presume that at this point there are no other Items than functions. */ + DBUG_ASSERT(cond_type == Item::FUNC_ITEM); + if (unlikely(cond_type != Item::FUNC_ITEM)) /* Safety */ + DBUG_RETURN(FALSE); + + /* Test if cond references only group-by or non-group fields. */ + Item_func *pred= (Item_func*) cond; + Item_func::Functype pred_type= pred->functype(); + DBUG_PRINT("info", ("Analyzing: %s", pred->func_name())); + if (pred_type == Item_func::MULT_EQUAL_FUNC) + { + /* + Check that each field in a multiple equality is either a constant or + it is a reference to the min/max argument, or it doesn't contain the + min/max argument at all. + */ + Item_equal_fields_iterator eq_it(*((Item_equal*)pred)); + Item *eq_item; + bool has_min_max= false, has_other= false; + while ((eq_item= eq_it++)) + { + if (min_max_arg_item->eq(eq_item->real_item(), 1)) + has_min_max= true; + else + has_other= true; + } + *has_min_max_arg= has_min_max || *has_min_max_arg; + *has_other_arg= has_other || *has_other_arg; + DBUG_RETURN(!(has_min_max && has_other)); + } + + Item **arguments= pred->arguments(); + Item *cur_arg; + bool has_min_max= false, has_other= false; + for (uint arg_idx= 0; arg_idx < pred->argument_count (); arg_idx++) + { + cur_arg= arguments[arg_idx]->real_item(); + DBUG_PRINT("info", ("cur_arg: %s", cur_arg->full_name())); + if (cur_arg->type() == Item::FIELD_ITEM) + { + if (min_max_arg_item->eq(cur_arg, 1)) + { + has_min_max= true; + /* + If pred references the MIN/MAX argument, check whether pred is a range + condition that compares the MIN/MAX argument with a constant. + */ + if (pred_type != Item_func::EQUAL_FUNC && + pred_type != Item_func::LT_FUNC && + pred_type != Item_func::LE_FUNC && + pred_type != Item_func::GT_FUNC && + pred_type != Item_func::GE_FUNC && + pred_type != Item_func::BETWEEN && + pred_type != Item_func::ISNULL_FUNC && + pred_type != Item_func::ISNOTNULL_FUNC && + pred_type != Item_func::EQ_FUNC && + pred_type != Item_func::NE_FUNC) + DBUG_RETURN(FALSE); + + /* Check that pred compares min_max_arg_item with a constant. */ + Item *args[3]; + bzero(args, 3 * sizeof(Item*)); + bool inv; + /* Test if this is a comparison of a field and a constant. */ + if (!simple_pred(pred, args, &inv)) + DBUG_RETURN(FALSE); + + if (args[0] && args[1]) // this is a binary function or BETWEEN + { + DBUG_ASSERT(pred->fixed_type_handler()); + DBUG_ASSERT(pred->fixed_type_handler()->is_bool_type()); + Item_bool_func *bool_func= (Item_bool_func*) pred; + Field *field= min_max_arg_item->field; + if (!args[2]) // this is a binary function + { + if (!field->can_optimize_group_min_max(bool_func, args[1])) + DBUG_RETURN(FALSE); + } + else // this is BETWEEN + { + if (!field->can_optimize_group_min_max(bool_func, args[1]) || + !field->can_optimize_group_min_max(bool_func, args[2])) + DBUG_RETURN(FALSE); + } + } + } + else + has_other= true; + } + else if (cur_arg->type() == Item::FUNC_ITEM) + { + if (!check_group_min_max_predicates(cur_arg, min_max_arg_item, image_type, + &has_min_max, &has_other)) + DBUG_RETURN(FALSE); + } + else if (cur_arg->const_item() && !cur_arg->is_expensive()) + { + /* + For predicates of the form "const OP expr" we also have to check 'expr' + to make a decision. + */ + continue; + } + else + DBUG_RETURN(FALSE); + if(has_min_max && has_other) + DBUG_RETURN(FALSE); + } + *has_min_max_arg= has_min_max || *has_min_max_arg; + *has_other_arg= has_other || *has_other_arg; + + DBUG_RETURN(TRUE); +} + + +/* + Get the SEL_ARG tree 'tree' for the keypart covering 'field', if + any. 'tree' must be a unique conjunction to ALL predicates in earlier + keyparts of 'keypart_tree'. + + E.g., if 'keypart_tree' is for a composite index (kp1,kp2) and kp2 + covers 'field', all these conditions satisfies the requirement: + + 1. "(kp1=2 OR kp1=3) AND kp2=10" => returns "kp2=10" + 2. "(kp1=2 AND kp2=10) OR (kp1=3 AND kp2=10)" => returns "kp2=10" + 3. "(kp1=2 AND (kp2=10 OR kp2=11)) OR (kp1=3 AND (kp2=10 OR kp2=11))" + => returns "kp2=10 OR kp2=11" + + whereas these do not + 1. "(kp1=2 AND kp2=10) OR kp1=3" + 2. "(kp1=2 AND kp2=10) OR (kp1=3 AND kp2=11)" + 3. "(kp1=2 AND kp2=10) OR (kp1=3 AND (kp2=10 OR kp2=11))" + + This function effectively tests requirement WA2. In combination with + a test that the returned tree has no more than one range it is also + a test of NGA3. + + @param[in] field The field we want the SEL_ARG tree for + @param[in] keypart_tree Root node of the SEL_ARG* tree for the index + @param[out] cur_range The SEL_ARG tree, if any, for the keypart + covering field 'keypart_field' + @retval true 'keypart_tree' contained a predicate for 'field' that + is not conjunction to all predicates on earlier keyparts + @retval false otherwise +*/ + +static bool +get_sel_arg_for_keypart(Field *field, + SEL_ARG *keypart_tree, + SEL_ARG **cur_range) +{ + if (keypart_tree == NULL) + return false; + if (keypart_tree->field->eq(field)) + { + *cur_range= keypart_tree; + return false; + } + + SEL_ARG *tree_first_range= NULL; + SEL_ARG *first_kp= keypart_tree->first(); + + for (SEL_ARG *cur_kp= first_kp; cur_kp; cur_kp= cur_kp->next) + { + SEL_ARG *curr_tree= NULL; + if (cur_kp->next_key_part) + { + if (get_sel_arg_for_keypart(field, + cur_kp->next_key_part, + &curr_tree)) + return true; + } + /* + Check if the SEL_ARG tree for 'field' is identical for all ranges in + 'keypart_tree + */ + if (cur_kp == first_kp) + tree_first_range= curr_tree; + else if (!all_same(tree_first_range, curr_tree)) + return true; + } + *cur_range= tree_first_range; + return false; +} + +/* + Extract a sequence of constants from a conjunction of equality predicates. + + SYNOPSIS + get_constant_key_infix() + index_info [in] Descriptor of the chosen index. + index_range_tree [in] Range tree for the chosen index + first_non_group_part [in] First index part after group attribute parts + min_max_arg_part [in] The keypart of the MIN/MAX argument if any + last_part [in] Last keypart of the index + thd [in] Current thread + key_infix [out] Infix of constants to be used for index lookup + key_infix_len [out] Length of the infix + first_non_infix_part [out] The first keypart after the infix (if any) + + DESCRIPTION + Test conditions (NGA1, NGA2, NGA3) from get_best_group_min_max(). Namely, + for each keypart field NG_i not in GROUP-BY, check that there is exactly one + constant equality predicate among conds with the form (NG_i = const_ci) or + (const_ci = NG_i).. In addition, there can only be one range when there is + such a gap. + Thus all the NGF_i attributes must fill the 'gap' between the last group-by + attribute and the MIN/MAX attribute in the index (if present). Also ensure + that there is only a single range on NGF_i (NGA3). If these + conditions hold, copy each constant from its corresponding predicate into + key_infix, in the order its NG_i attribute appears in the index, and update + key_infix_len with the total length of the key parts in key_infix. + + RETURN + TRUE if the index passes the test + FALSE o/w +*/ +static bool +get_constant_key_infix(KEY *index_info, SEL_ARG *index_range_tree, + KEY_PART_INFO *first_non_group_part, + KEY_PART_INFO *min_max_arg_part, + KEY_PART_INFO *last_part, THD *thd, + uchar *key_infix, uint *key_infix_len, + KEY_PART_INFO **first_non_infix_part) +{ + KEY_PART_INFO *cur_part; + /* End part for the first loop below. */ + KEY_PART_INFO *end_part= min_max_arg_part ? min_max_arg_part : last_part; + + *key_infix_len= 0; + uchar *key_ptr= key_infix; + for (cur_part= first_non_group_part; cur_part != end_part; cur_part++) + { + SEL_ARG *cur_range= NULL; + /* + Check NGA3: + 1. get_sel_arg_for_keypart gets the range tree for the 'field' and also + checks for a unique conjunction of this tree with all the predicates + on the earlier keyparts in the index. + 2. Check for multiple ranges on the found keypart tree. + + We assume that index_range_tree points to the leftmost keypart in + the index. + */ + if (get_sel_arg_for_keypart(cur_part->field, index_range_tree, + &cur_range)) + return false; + + if (cur_range && cur_range->elements > 1) + return false; + + if (!cur_range || cur_range->type != SEL_ARG::KEY_RANGE) + { + if (min_max_arg_part) + return false; /* The current keypart has no range predicates at all. */ + else + { + *first_non_infix_part= cur_part; + return true; + } + } + + if ((cur_range->min_flag & NO_MIN_RANGE) || + (cur_range->max_flag & NO_MAX_RANGE) || + (cur_range->min_flag & NEAR_MIN) || (cur_range->max_flag & NEAR_MAX)) + return false; + + uint field_length= cur_part->store_length; + if (cur_range->maybe_null && + cur_range->min_value[0] && cur_range->max_value[0]) + { + /* + cur_range specifies 'IS NULL'. In this case the argument points + to a "null value" (is_null_string) that may not always be long + enough for a direct memcpy to a field. + */ + DBUG_ASSERT (field_length > 0); + *key_ptr= 1; + bzero(key_ptr+1,field_length-1); + key_ptr+= field_length; + *key_infix_len+= field_length; + } + else if (memcmp(cur_range->min_value, cur_range->max_value, field_length) == 0) + { /* cur_range specifies an equality condition. */ + memcpy(key_ptr, cur_range->min_value, field_length); + key_ptr+= field_length; + *key_infix_len+= field_length; + } + else + return false; + } + + if (!min_max_arg_part && (cur_part == last_part)) + *first_non_infix_part= last_part; + + return TRUE; +} + + +/* + Find the key part referenced by a field. + + SYNOPSIS + get_field_keypart() + index descriptor of an index + field field that possibly references some key part in index + + NOTES + The return value can be used to get a KEY_PART_INFO pointer by + part= index->key_part + get_field_keypart(...) - 1; + + RETURN + Positive number which is the consecutive number of the key part, or + 0 if field does not reference any index field. +*/ + +static inline uint +get_field_keypart(KEY *index, Field *field) +{ + KEY_PART_INFO *part, *end; + + for (part= index->key_part, + end= part + field->table->actual_n_key_parts(index); + part < end; part++) + { + if (field->eq(part->field)) + return (uint)(part - index->key_part + 1); + } + return 0; +} + + +/* + Compute the cost of a quick_group_min_max_select for a particular index. + + SYNOPSIS + cost_group_min_max() + table [in] The table being accessed + index_info [in] The index used to access the table + used_key_parts [in] Number of key parts used to access the index + group_key_parts [in] Number of index key parts in the group prefix + range_tree [in] Tree of ranges for all indexes + index_tree [in] The range tree for the current index + quick_prefix_records [in] Number of records retrieved by the internally + used quick range select if any + have_min [in] True if there is a MIN function + have_max [in] True if there is a MAX function + read_cost [out] The cost to retrieve rows via this quick select + records [out] The number of rows retrieved + + DESCRIPTION + This method computes the access cost of a TRP_GROUP_MIN_MAX instance and + the number of rows returned. + + NOTES + The cost computation distinguishes several cases: + 1) No equality predicates over non-group attributes (thus no key_infix). + If groups are bigger than blocks on the average, then we assume that it + is very unlikely that block ends are aligned with group ends, thus even + if we look for both MIN and MAX keys, all pairs of neighbor MIN/MAX + keys, except for the first MIN and the last MAX keys, will be in the + same block. If groups are smaller than blocks, then we are going to + read all blocks. + 2) There are equality predicates over non-group attributes. + In this case the group prefix is extended by additional constants, and + as a result the min/max values are inside sub-groups of the original + groups. The number of blocks that will be read depends on whether the + ends of these sub-groups will be contained in the same or in different + blocks. We compute the probability for the two ends of a subgroup to be + in two different blocks as the ratio of: + - the number of positions of the left-end of a subgroup inside a group, + such that the right end of the subgroup is past the end of the buffer + containing the left-end, and + - the total number of possible positions for the left-end of the + subgroup, which is the number of keys in the containing group. + We assume it is very unlikely that two ends of subsequent subgroups are + in the same block. + 3) The are range predicates over the group attributes. + Then some groups may be filtered by the range predicates. We use the + selectivity of the range predicates to decide how many groups will be + filtered. + + TODO + - Take into account the optional range predicates over the MIN/MAX + argument. + - Check if we have a PK index and we use all cols - then each key is a + group, and it will be better to use an index scan. + + RETURN + None +*/ + +void cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts, + uint group_key_parts, SEL_TREE *range_tree, + SEL_ARG *index_tree, ha_rows quick_prefix_records, + bool have_min, bool have_max, + double *read_cost, ha_rows *records) +{ + ha_rows table_records; + ha_rows num_groups; + ha_rows num_blocks; + uint keys_per_block; + ha_rows keys_per_group; + ha_rows keys_per_subgroup; /* Average number of keys in sub-groups */ + /* formed by a key infix. */ + double p_overlap; /* Probability that a sub-group overlaps two blocks. */ + double quick_prefix_selectivity; + double io_cost; + DBUG_ENTER("cost_group_min_max"); + + table_records= table->stat_records(); + /* Assume block is 75 % full */ + keys_per_block= (uint) (table->file->stats.block_size * 3 / 4 / + (index_info->key_length + table->file->ref_length) + + 1); + num_blocks= (ha_rows)(table_records / keys_per_block) + 1; + + /* Compute the number of keys in a group. */ + if (!group_key_parts) + { + /* Summary over the whole table */ + keys_per_group= table_records; + } + else + { + keys_per_group= (ha_rows) index_info->actual_rec_per_key(group_key_parts - + 1); + } + + if (keys_per_group == 0) /* If there is no statistics try to guess */ + /* each group contains 10% of all records */ + keys_per_group= (table_records / 10) + 1; + num_groups= (table_records / keys_per_group) + 1; + + /* Apply the selectivity of the quick select for group prefixes. */ + if (range_tree && (quick_prefix_records != HA_POS_ERROR)) + { + quick_prefix_selectivity= (double) quick_prefix_records / + (double) table_records; + num_groups= (ha_rows) rint(num_groups * quick_prefix_selectivity); + set_if_bigger(num_groups, 1); + } + + if (used_key_parts > group_key_parts) + { /* + Compute the probability that two ends of a subgroup are inside + different blocks. + */ + keys_per_subgroup= (ha_rows) index_info->actual_rec_per_key(used_key_parts - 1); + if (keys_per_subgroup >= keys_per_block) /* If a subgroup is bigger than */ + p_overlap= 1.0; /* a block, it will overlap at least two blocks. */ + else + { + double blocks_per_group= (double) num_blocks / (double) num_groups; + p_overlap= (blocks_per_group * (keys_per_subgroup - 1)) / keys_per_group; + p_overlap= MY_MIN(p_overlap, 1.0); + } + io_cost= (double) MY_MIN(num_groups * (1 + p_overlap), num_blocks); + } + else + io_cost= (keys_per_group > keys_per_block) ? + (have_min && have_max) ? (double) (num_groups + 1) : + (double) num_groups : + (double) num_blocks; + + /* + CPU cost must be comparable to that of an index scan as computed + in SQL_SELECT::test_quick_select(). When the groups are small, + e.g. for a unique index, using index scan will be cheaper since it + reads the next record without having to re-position to it on every + group. To make the CPU cost reflect this, we estimate the CPU cost + as the sum of: + 1. Cost for evaluating the condition (similarly as for index scan). + 2. Cost for navigating the index structure (assuming a b-tree). + Note: We only add the cost for one comparision per block. For a + b-tree the number of comparisons will be larger. + TODO: This cost should be provided by the storage engine. + */ + const double tree_traversal_cost= + ceil(log(static_cast<double>(table_records))/ + log(static_cast<double>(keys_per_block))) * + 1/(2*TIME_FOR_COMPARE); + + const double cpu_cost= num_groups * + (tree_traversal_cost + 1/TIME_FOR_COMPARE_IDX); + + *read_cost= io_cost + cpu_cost; + *records= num_groups; + + DBUG_PRINT("info", + ("table rows: %lu keys/block: %u keys/group: %lu " + "result rows: %lu blocks: %lu", + (ulong) table_records, keys_per_block, (ulong) keys_per_group, + (ulong) *records, (ulong) num_blocks)); + DBUG_VOID_RETURN; +} + + +/* + Construct a new quick select object for queries with group by with min/max. + + SYNOPSIS + TRP_GROUP_MIN_MAX::make_quick() + param Parameter from test_quick_select + retrieve_full_rows ignored + parent_alloc Memory pool to use, if any. + + NOTES + Make_quick ignores the retrieve_full_rows parameter because + QUICK_GROUP_MIN_MAX_SELECT always performs 'index only' scans. + The other parameter are ignored as well because all necessary + data to create the QUICK object is computed at this TRP creation + time. + + RETURN + New QUICK_GROUP_MIN_MAX_SELECT object if successfully created, + NULL otherwise. +*/ + +QUICK_SELECT_I * +TRP_GROUP_MIN_MAX::make_quick(PARAM *param, bool retrieve_full_rows, + MEM_ROOT *parent_alloc) +{ + QUICK_GROUP_MIN_MAX_SELECT *quick; + DBUG_ENTER("TRP_GROUP_MIN_MAX::make_quick"); + + quick= new QUICK_GROUP_MIN_MAX_SELECT(param->table, + param->thd->lex->current_select->join, + have_min, have_max, + have_agg_distinct, min_max_arg_part, + group_prefix_len, group_key_parts, + used_key_parts, index_info, index, + read_cost, records, key_infix_len, + key_infix, parent_alloc, is_index_scan); + if (!quick) + DBUG_RETURN(NULL); + + if (quick->init()) + { + delete quick; + DBUG_RETURN(NULL); + } + + if (range_tree) + { + DBUG_ASSERT(quick_prefix_records > 0); + if (quick_prefix_records == HA_POS_ERROR) + quick->quick_prefix_select= NULL; /* Can't construct a quick select. */ + else + /* Make a QUICK_RANGE_SELECT to be used for group prefix retrieval. */ + quick->quick_prefix_select= get_quick_select(param, param_idx, + index_tree, + HA_MRR_USE_DEFAULT_IMPL, 0, + &quick->alloc); + + /* + Extract the SEL_ARG subtree that contains only ranges for the MIN/MAX + attribute, and create an array of QUICK_RANGES to be used by the + new quick select. + */ + if (min_max_arg_part) + { + SEL_ARG *min_max_range= index_tree; + while (min_max_range) /* Find the tree for the MIN/MAX key part. */ + { + if (min_max_range->field->eq(min_max_arg_part->field)) + break; + min_max_range= min_max_range->next_key_part; + } + /* Scroll to the leftmost interval for the MIN/MAX argument. */ + while (min_max_range && min_max_range->prev) + min_max_range= min_max_range->prev; + /* Create an array of QUICK_RANGEs for the MIN/MAX argument. */ + while (min_max_range) + { + if (quick->add_range(min_max_range)) + { + delete quick; + quick= NULL; + DBUG_RETURN(NULL); + } + min_max_range= min_max_range->next; + } + } + } + else + quick->quick_prefix_select= NULL; + + quick->update_key_stat(); + quick->adjust_prefix_ranges(); + + DBUG_RETURN(quick); +} + + +/* + Construct new quick select for group queries with min/max. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::QUICK_GROUP_MIN_MAX_SELECT() + table The table being accessed + join Descriptor of the current query + have_min TRUE if the query selects a MIN function + have_max TRUE if the query selects a MAX function + min_max_arg_part The only argument field of all MIN/MAX functions + group_prefix_len Length of all key parts in the group prefix + prefix_key_parts All key parts in the group prefix + index_info The index chosen for data access + use_index The id of index_info + read_cost Cost of this access method + records Number of records returned + key_infix_len Length of the key infix appended to the group prefix + key_infix Infix of constants from equality predicates + parent_alloc Memory pool for this and quick_prefix_select data + is_index_scan get the next different key not by jumping on it via + index read, but by scanning until the end of the + rows with equal key value. + + RETURN + None +*/ + +QUICK_GROUP_MIN_MAX_SELECT:: +QUICK_GROUP_MIN_MAX_SELECT(TABLE *table, JOIN *join_arg, bool have_min_arg, + bool have_max_arg, bool have_agg_distinct_arg, + KEY_PART_INFO *min_max_arg_part_arg, + uint group_prefix_len_arg, uint group_key_parts_arg, + uint used_key_parts_arg, KEY *index_info_arg, + uint use_index, double read_cost_arg, + ha_rows records_arg, uint key_infix_len_arg, + uchar *key_infix_arg, MEM_ROOT *parent_alloc, + bool is_index_scan_arg) + :file(table->file), join(join_arg), index_info(index_info_arg), + group_prefix_len(group_prefix_len_arg), + group_key_parts(group_key_parts_arg), have_min(have_min_arg), + have_max(have_max_arg), have_agg_distinct(have_agg_distinct_arg), + seen_first_key(FALSE), min_max_arg_part(min_max_arg_part_arg), + key_infix(key_infix_arg), key_infix_len(key_infix_len_arg), + min_functions_it(NULL), max_functions_it(NULL), + is_index_scan(is_index_scan_arg) +{ + head= table; + index= use_index; + record= head->record[0]; + tmp_record= head->record[1]; + read_time= read_cost_arg; + records= records_arg; + used_key_parts= used_key_parts_arg; + real_key_parts= used_key_parts_arg; + real_prefix_len= group_prefix_len + key_infix_len; + group_prefix= NULL; + min_max_arg_len= min_max_arg_part ? min_max_arg_part->store_length : 0; + + /* + We can't have parent_alloc set as the init function can't handle this case + yet. + */ + DBUG_ASSERT(!parent_alloc); + if (!parent_alloc) + { + THD *thd= join->thd; + init_sql_alloc(key_memory_quick_range_select_root, &alloc, + thd->variables.range_alloc_block_size, 0, MYF(MY_THREAD_SPECIFIC)); + thd->mem_root= &alloc; + } + else + bzero(&alloc, sizeof(MEM_ROOT)); // ensure that it's not used +} + + +/* + Do post-constructor initialization. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::init() + + DESCRIPTION + The method performs initialization that cannot be done in the constructor + such as memory allocations that may fail. It allocates memory for the + group prefix and inifix buffers, and for the lists of MIN/MAX item to be + updated during execution. + + RETURN + 0 OK + other Error code +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::init() +{ + if (group_prefix) /* Already initialized. */ + return 0; + + /* + We allocate one byte more to serve the case when the last field in + the buffer is compared using uint3korr (e.g. a Field_newdate field) + */ + if (!(last_prefix= (uchar*) alloc_root(&alloc, group_prefix_len+1))) + return 1; + /* + We may use group_prefix to store keys with all select fields, so allocate + enough space for it. + We allocate one byte more to serve the case when the last field in + the buffer is compared using uint3korr (e.g. a Field_newdate field) + */ + if (!(group_prefix= (uchar*) alloc_root(&alloc, + real_prefix_len+min_max_arg_len+1))) + return 1; + + if (key_infix_len > 0) + { + /* + The memory location pointed to by key_infix will be deleted soon, so + allocate a new buffer and copy the key_infix into it. + */ + uchar *tmp_key_infix= (uchar*) alloc_root(&alloc, key_infix_len); + if (!tmp_key_infix) + return 1; + memcpy(tmp_key_infix, this->key_infix, key_infix_len); + this->key_infix= tmp_key_infix; + } + + if (min_max_arg_part) + { + if (my_init_dynamic_array(PSI_INSTRUMENT_ME, &min_max_ranges, + sizeof(QUICK_RANGE*), 16, 16, + MYF(MY_THREAD_SPECIFIC))) + return 1; + + if (have_min) + { + if (!(min_functions= new List<Item_sum>)) + return 1; + } + else + min_functions= NULL; + if (have_max) + { + if (!(max_functions= new List<Item_sum>)) + return 1; + } + else + max_functions= NULL; + + Item_sum *min_max_item; + Item_sum **func_ptr= join->sum_funcs; + while ((min_max_item= *(func_ptr++))) + { + if (have_min && (min_max_item->sum_func() == Item_sum::MIN_FUNC)) + min_functions->push_back(min_max_item); + else if (have_max && (min_max_item->sum_func() == Item_sum::MAX_FUNC)) + max_functions->push_back(min_max_item); + } + + if (have_min) + { + if (!(min_functions_it= new List_iterator<Item_sum>(*min_functions))) + return 1; + } + + if (have_max) + { + if (!(max_functions_it= new List_iterator<Item_sum>(*max_functions))) + return 1; + } + } + else + min_max_ranges.elements= 0; + + return 0; +} + + +QUICK_GROUP_MIN_MAX_SELECT::~QUICK_GROUP_MIN_MAX_SELECT() +{ + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::~QUICK_GROUP_MIN_MAX_SELECT"); + if (file->inited != handler::NONE) + { + DBUG_ASSERT(file == head->file); + head->file->ha_end_keyread(); + /* + There may be a code path when the same table was first accessed by index, + then the index is closed, and the table is scanned (order by + loose scan). + */ + file->ha_index_or_rnd_end(); + } + if (min_max_arg_part) + delete_dynamic(&min_max_ranges); + free_root(&alloc,MYF(0)); + delete min_functions_it; + delete max_functions_it; + delete quick_prefix_select; + DBUG_VOID_RETURN; +} + + +/* + Eventually create and add a new quick range object. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::add_range() + sel_range Range object from which a + + NOTES + Construct a new QUICK_RANGE object from a SEL_ARG object, and + add it to the array min_max_ranges. If sel_arg is an infinite + range, e.g. (x < 5 or x > 4), then skip it and do not construct + a quick range. + + RETURN + FALSE on success + TRUE otherwise +*/ + +bool QUICK_GROUP_MIN_MAX_SELECT::add_range(SEL_ARG *sel_range) +{ + QUICK_RANGE *range; + uint range_flag= sel_range->min_flag | sel_range->max_flag; + + /* Skip (-inf,+inf) ranges, e.g. (x < 5 or x > 4). */ + if ((range_flag & NO_MIN_RANGE) && (range_flag & NO_MAX_RANGE)) + return FALSE; + + if (!(sel_range->min_flag & NO_MIN_RANGE) && + !(sel_range->max_flag & NO_MAX_RANGE)) + { + if (sel_range->maybe_null && + sel_range->min_value[0] && sel_range->max_value[0]) + range_flag|= NULL_RANGE; /* IS NULL condition */ + else if (memcmp(sel_range->min_value, sel_range->max_value, + min_max_arg_len) == 0) + range_flag|= EQ_RANGE; /* equality condition */ + } + range= new QUICK_RANGE(join->thd, sel_range->min_value, min_max_arg_len, + make_keypart_map(sel_range->part), + sel_range->max_value, min_max_arg_len, + make_keypart_map(sel_range->part), + range_flag); + if (!range) + return TRUE; + if (insert_dynamic(&min_max_ranges, (uchar*)&range)) + return TRUE; + return FALSE; +} + + +/* + Opens the ranges if there are more conditions in quick_prefix_select than + the ones used for jumping through the prefixes. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges() + + NOTES + quick_prefix_select is made over the conditions on the whole key. + It defines a number of ranges of length x. + However when jumping through the prefixes we use only the the first + few most significant keyparts in the range key. However if there + are more keyparts to follow the ones we are using we must make the + condition on the key inclusive (because x < "ab" means + x[0] < 'a' OR (x[0] == 'a' AND x[1] < 'b'). + To achive the above we must turn off the NEAR_MIN/NEAR_MAX +*/ +void QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges () +{ + if (quick_prefix_select && + group_prefix_len < quick_prefix_select->max_used_key_length) + { + DYNAMIC_ARRAY *arr; + uint inx; + + for (inx= 0, arr= &quick_prefix_select->ranges; inx < arr->elements; inx++) + { + QUICK_RANGE *range; + + get_dynamic(arr, (uchar*)&range, inx); + range->flag &= ~(NEAR_MIN | NEAR_MAX); + } + } +} + + +/* + Determine the total number and length of the keys that will be used for + index lookup. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::update_key_stat() + + DESCRIPTION + The total length of the keys used for index lookup depends on whether + there are any predicates referencing the min/max argument, and/or if + the min/max argument field can be NULL. + This function does an optimistic analysis whether the search key might + be extended by a constant for the min/max keypart. It is 'optimistic' + because during actual execution it may happen that a particular range + is skipped, and then a shorter key will be used. However this is data + dependent and can't be easily estimated here. + + RETURN + None +*/ + +void QUICK_GROUP_MIN_MAX_SELECT::update_key_stat() +{ + max_used_key_length= real_prefix_len; + if (min_max_ranges.elements > 0) + { + QUICK_RANGE *cur_range; + if (have_min) + { /* Check if the right-most range has a lower boundary. */ + get_dynamic(&min_max_ranges, (uchar*)&cur_range, + min_max_ranges.elements - 1); + if (!(cur_range->flag & NO_MIN_RANGE)) + { + max_used_key_length+= min_max_arg_len; + used_key_parts++; + return; + } + } + if (have_max) + { /* Check if the left-most range has an upper boundary. */ + get_dynamic(&min_max_ranges, (uchar*)&cur_range, 0); + if (!(cur_range->flag & NO_MAX_RANGE)) + { + max_used_key_length+= min_max_arg_len; + used_key_parts++; + return; + } + } + } + else if (have_min && min_max_arg_part && + min_max_arg_part->field->real_maybe_null()) + { + /* + If a MIN/MAX argument value is NULL, we can quickly determine + that we're in the beginning of the next group, because NULLs + are always < any other value. This allows us to quickly + determine the end of the current group and jump to the next + group (see next_min()) and thus effectively increases the + usable key length. + */ + max_used_key_length+= min_max_arg_len; + used_key_parts++; + } +} + + +/* + Initialize a quick group min/max select for key retrieval. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::reset() + + DESCRIPTION + Initialize the index chosen for access and find and store the prefix + of the last group. The method is expensive since it performs disk access. + + RETURN + 0 OK + other Error code +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::reset(void) +{ + int result; + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::reset"); + + seen_first_key= FALSE; + head->file->ha_start_keyread(index); /* We need only the key attributes */ + + if ((result= file->ha_index_init(index,1))) + { + head->file->print_error(result, MYF(0)); + DBUG_RETURN(result); + } + if (quick_prefix_select && quick_prefix_select->reset()) + DBUG_RETURN(1); + result= file->ha_index_last(record); + if (result == HA_ERR_END_OF_FILE) + DBUG_RETURN(0); + /* Save the prefix of the last group. */ + key_copy(last_prefix, record, index_info, group_prefix_len); + + DBUG_RETURN(0); +} + + + +/* + Get the next key containing the MIN and/or MAX key for the next group. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::get_next() + + DESCRIPTION + The method finds the next subsequent group of records that satisfies the + query conditions and finds the keys that contain the MIN/MAX values for + the key part referenced by the MIN/MAX function(s). Once a group and its + MIN/MAX values are found, store these values in the Item_sum objects for + the MIN/MAX functions. The rest of the values in the result row are stored + in the Item_field::result_field of each select field. If the query does + not contain MIN and/or MAX functions, then the function only finds the + group prefix, which is a query answer itself. + + NOTES + If both MIN and MAX are computed, then we use the fact that if there is + no MIN key, there can't be a MAX key as well, so we can skip looking + for a MAX key in this case. + + RETURN + 0 on success + HA_ERR_END_OF_FILE if returned all keys + other if some error occurred +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::get_next() +{ + int min_res= 0; + int max_res= 0; +#ifdef HPUX11 + /* + volatile is required by a bug in the HP compiler due to which the + last test of result fails. + */ + volatile int result; +#else + int result; +#endif + int is_last_prefix= 0; + + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::get_next"); + + /* + Loop until a group is found that satisfies all query conditions or the last + group is reached. + */ + do + { + result= next_prefix(); + /* + Check if this is the last group prefix. Notice that at this point + this->record contains the current prefix in record format. + */ + if (!result) + { + is_last_prefix= key_cmp(index_info->key_part, last_prefix, + group_prefix_len); + DBUG_ASSERT(is_last_prefix <= 0); + } + else + { + if (result == HA_ERR_KEY_NOT_FOUND) + continue; + break; + } + + if (have_min) + { + min_res= next_min(); + if (min_res == 0) + update_min_result(); + } + /* If there is no MIN in the group, there is no MAX either. */ + if ((have_max && !have_min) || + (have_max && have_min && (min_res == 0))) + { + max_res= next_max(); + if (max_res == 0) + update_max_result(); + /* If a MIN was found, a MAX must have been found as well. */ + DBUG_ASSERT((have_max && !have_min) || + (have_max && have_min && (max_res == 0))); + } + /* + If this is just a GROUP BY or DISTINCT without MIN or MAX and there + are equality predicates for the key parts after the group, find the + first sub-group with the extended prefix. + */ + if (!have_min && !have_max && key_infix_len > 0) + result= file->ha_index_read_map(record, group_prefix, + make_prev_keypart_map(real_key_parts), + HA_READ_KEY_EXACT); + + result= have_min ? min_res : have_max ? max_res : result; + } while ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) && + is_last_prefix != 0); + + if (result == HA_ERR_KEY_NOT_FOUND) + result= HA_ERR_END_OF_FILE; + + DBUG_RETURN(result); +} + + +/* + Retrieve the minimal key in the next group. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::next_min() + + DESCRIPTION + Find the minimal key within this group such that the key satisfies the query + conditions and NULL semantics. The found key is loaded into this->record. + + IMPLEMENTATION + Depending on the values of min_max_ranges.elements, key_infix_len, and + whether there is a NULL in the MIN field, this function may directly + return without any data access. In this case we use the key loaded into + this->record by the call to this->next_prefix() just before this call. + + RETURN + 0 on success + HA_ERR_KEY_NOT_FOUND if no MIN key was found that fulfills all conditions. + HA_ERR_END_OF_FILE - "" - + other if some error occurred +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::next_min() +{ + int result= 0; + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_min"); + + /* Find the MIN key using the eventually extended group prefix. */ + if (min_max_ranges.elements > 0) + { + if ((result= next_min_in_range())) + DBUG_RETURN(result); + } + else + { + /* Apply the constant equality conditions to the non-group select fields */ + if (key_infix_len > 0) + { + if ((result= + file->ha_index_read_map(record, group_prefix, + make_prev_keypart_map(real_key_parts), + HA_READ_KEY_EXACT))) + DBUG_RETURN(result); + } + + /* + If the min/max argument field is NULL, skip subsequent rows in the same + group with NULL in it. Notice that: + - if the first row in a group doesn't have a NULL in the field, no row + in the same group has (because NULL < any other value), + - min_max_arg_part->field->ptr points to some place in 'record'. + */ + if (min_max_arg_part && min_max_arg_part->field->is_null()) + { + uchar *tmp_key_buff= (uchar*)my_alloca(max_used_key_length); + /* Find the first subsequent record without NULL in the MIN/MAX field. */ + key_copy(tmp_key_buff, record, index_info, max_used_key_length); + result= file->ha_index_read_map(record, tmp_key_buff, + make_keypart_map(real_key_parts), + HA_READ_AFTER_KEY); + /* + Check if the new record belongs to the current group by comparing its + prefix with the group's prefix. If it is from the next group, then the + whole group has NULLs in the MIN/MAX field, so use the first record in + the group as a result. + TODO: + It is possible to reuse this new record as the result candidate for the + next call to next_min(), and to save one lookup in the next call. For + this add a new member 'this->next_group_prefix'. + */ + if (!result) + { + if (key_cmp(index_info->key_part, group_prefix, real_prefix_len)) + key_restore(record, tmp_key_buff, index_info, 0); + } + else if (result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) + result= 0; /* There is a result in any case. */ + my_afree(tmp_key_buff); + } + } + + /* + If the MIN attribute is non-nullable, this->record already contains the + MIN key in the group, so just return. + */ + DBUG_RETURN(result); +} + + +/* + Retrieve the maximal key in the next group. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::next_max() + + DESCRIPTION + Lookup the maximal key of the group, and store it into this->record. + + RETURN + 0 on success + HA_ERR_KEY_NOT_FOUND if no MAX key was found that fulfills all conditions. + HA_ERR_END_OF_FILE - "" - + other if some error occurred +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::next_max() +{ + int result; + + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_max"); + + /* Get the last key in the (possibly extended) group. */ + if (min_max_ranges.elements > 0) + result= next_max_in_range(); + else + result= file->ha_index_read_map(record, group_prefix, + make_prev_keypart_map(real_key_parts), + HA_READ_PREFIX_LAST); + DBUG_RETURN(result); +} + + +/** + Find the next different key value by skiping all the rows with the same key + value. + + Implements a specialized loose index access method for queries + containing aggregate functions with distinct of the form: + SELECT [SUM|COUNT|AVG](DISTINCT a,...) FROM t + This method comes to replace the index scan + Unique class + (distinct selection) for loose index scan that visits all the rows of a + covering index instead of jumping in the beginning of each group. + TODO: Placeholder function. To be replaced by a handler API call + + @param is_index_scan hint to use index scan instead of random index read + to find the next different value. + @param file table handler + @param key_part group key to compare + @param record row data + @param group_prefix current key prefix data + @param group_prefix_len length of the current key prefix data + @param group_key_parts number of the current key prefix columns + @return status + @retval 0 success + @retval !0 failure +*/ + +static int index_next_different (bool is_index_scan, handler *file, + KEY_PART_INFO *key_part, uchar * record, + const uchar * group_prefix, + uint group_prefix_len, + uint group_key_parts) +{ + if (is_index_scan) + { + int result= 0; + + while (!key_cmp (key_part, group_prefix, group_prefix_len)) + { + result= file->ha_index_next(record); + if (result) + return(result); + } + return result; + } + else + return file->ha_index_read_map(record, group_prefix, + make_prev_keypart_map(group_key_parts), + HA_READ_AFTER_KEY); +} + + +/* + Determine the prefix of the next group. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::next_prefix() + + DESCRIPTION + Determine the prefix of the next group that satisfies the query conditions. + If there is a range condition referencing the group attributes, use a + QUICK_RANGE_SELECT object to retrieve the *first* key that satisfies the + condition. If there is a key infix of constants, append this infix + immediately after the group attributes. The possibly extended prefix is + stored in this->group_prefix. The first key of the found group is stored in + this->record, on which relies this->next_min(). + + RETURN + 0 on success + HA_ERR_KEY_NOT_FOUND if there is no key with the formed prefix + HA_ERR_END_OF_FILE if there are no more keys + other if some error occurred +*/ +int QUICK_GROUP_MIN_MAX_SELECT::next_prefix() +{ + int result; + DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_prefix"); + + if (quick_prefix_select) + { + uchar *cur_prefix= seen_first_key ? group_prefix : NULL; + if ((result= quick_prefix_select->get_next_prefix(group_prefix_len, + group_key_parts, + cur_prefix))) + DBUG_RETURN(result); + seen_first_key= TRUE; + } + else + { + if (!seen_first_key) + { + result= file->ha_index_first(record); + if (result) + DBUG_RETURN(result); + seen_first_key= TRUE; + } + else + { + /* Load the first key in this group into record. */ + result= index_next_different (is_index_scan, file, index_info->key_part, + record, group_prefix, group_prefix_len, + group_key_parts); + if (result) + DBUG_RETURN(result); + } + } + + /* Save the prefix of this group for subsequent calls. */ + key_copy(group_prefix, record, index_info, group_prefix_len); + /* Append key_infix to group_prefix. */ + if (key_infix_len > 0) + memcpy(group_prefix + group_prefix_len, + key_infix, key_infix_len); + + DBUG_RETURN(0); +} + + +/** + Allocate a temporary buffer, populate the buffer using the group prefix key + and the min/max field key, and compare the result to the current key pointed + by index_info. + + @param key - the min or max field key + @param length - length of "key" +*/ +int +QUICK_GROUP_MIN_MAX_SELECT::cmp_min_max_key(const uchar *key, uint16 length) +{ + /* + Allocate a buffer. + Note, we allocate one extra byte, because some of Field_xxx::cmp(), + e.g. Field_newdate::cmp(), use uint3korr() which actually read four bytes + and then bit-and the read value with 0xFFFFFF. + See "MDEV-7920 main.group_min_max fails ... with valgrind" for details. + */ + uchar *buffer= (uchar*) my_alloca(real_prefix_len + min_max_arg_len + 1); + /* Concatenate the group prefix key and the min/max field key */ + memcpy(buffer, group_prefix, real_prefix_len); + memcpy(buffer + real_prefix_len, key, length); + /* Compare the key pointed by key_info to the created key */ + int cmp_res= key_cmp(index_info->key_part, buffer, + real_prefix_len + min_max_arg_len); + my_afree(buffer); + return cmp_res; +} + + +/* + Find the minimal key in a group that satisfies some range conditions for the + min/max argument field. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::next_min_in_range() + + DESCRIPTION + Given the sequence of ranges min_max_ranges, find the minimal key that is + in the left-most possible range. If there is no such key, then the current + group does not have a MIN key that satisfies the WHERE clause. If a key is + found, its value is stored in this->record. + + RETURN + 0 on success + HA_ERR_KEY_NOT_FOUND if there is no key with the given prefix in any of + the ranges + HA_ERR_END_OF_FILE - "" - + other if some error +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::next_min_in_range() +{ + ha_rkey_function find_flag; + key_part_map keypart_map; + QUICK_RANGE *cur_range; + bool found_null= FALSE; + int result= HA_ERR_KEY_NOT_FOUND; + + DBUG_ASSERT(min_max_ranges.elements > 0); + + for (uint range_idx= 0; range_idx < min_max_ranges.elements; range_idx++) + { /* Search from the left-most range to the right. */ + get_dynamic(&min_max_ranges, (uchar*)&cur_range, range_idx); + + /* + If the current value for the min/max argument is bigger than the right + boundary of cur_range, there is no need to check this range. + */ + if (range_idx != 0 && !(cur_range->flag & NO_MAX_RANGE) && + (key_cmp(min_max_arg_part, (const uchar*) cur_range->max_key, + min_max_arg_len) == 1)) + continue; + + if (cur_range->flag & NO_MIN_RANGE) + { + keypart_map= make_prev_keypart_map(real_key_parts); + find_flag= HA_READ_KEY_EXACT; + } + else + { + /* Extend the search key with the lower boundary for this range. */ + memcpy(group_prefix + real_prefix_len, cur_range->min_key, + cur_range->min_length); + keypart_map= make_keypart_map(real_key_parts); + find_flag= (cur_range->flag & (EQ_RANGE | NULL_RANGE)) ? + HA_READ_KEY_EXACT : (cur_range->flag & NEAR_MIN) ? + HA_READ_AFTER_KEY : HA_READ_KEY_OR_NEXT; + } + + result= file->ha_index_read_map(record, group_prefix, keypart_map, + find_flag); + if (result) + { + if ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) && + (cur_range->flag & (EQ_RANGE | NULL_RANGE))) + continue; /* Check the next range. */ + + /* + In all other cases (HA_ERR_*, HA_READ_KEY_EXACT with NO_MIN_RANGE, + HA_READ_AFTER_KEY, HA_READ_KEY_OR_NEXT) if the lookup failed for this + range, it can't succeed for any other subsequent range. + */ + break; + } + + /* A key was found. */ + if (cur_range->flag & EQ_RANGE) + break; /* No need to perform the checks below for equal keys. */ + + if (cur_range->flag & NULL_RANGE) + { + /* + Remember this key, and continue looking for a non-NULL key that + satisfies some other condition. + */ + memcpy(tmp_record, record, head->s->rec_buff_length); + found_null= TRUE; + continue; + } + + /* Check if record belongs to the current group. */ + if (key_cmp(index_info->key_part, group_prefix, real_prefix_len)) + { + result= HA_ERR_KEY_NOT_FOUND; + continue; + } + + /* If there is an upper limit, check if the found key is in the range. */ + if ( !(cur_range->flag & NO_MAX_RANGE) ) + { + int cmp_res= cmp_min_max_key(cur_range->max_key, cur_range->max_length); + /* + The key is outside of the range if: + the interval is open and the key is equal to the maximum boundry + or + the key is greater than the maximum + */ + if (((cur_range->flag & NEAR_MAX) && cmp_res == 0) || + cmp_res > 0) + { + result= HA_ERR_KEY_NOT_FOUND; + continue; + } + } + /* If we got to this point, the current key qualifies as MIN. */ + DBUG_ASSERT(result == 0); + break; + } + /* + If there was a key with NULL in the MIN/MAX field, and there was no other + key without NULL from the same group that satisfies some other condition, + then use the key with the NULL. + */ + if (found_null && result) + { + memcpy(record, tmp_record, head->s->rec_buff_length); + result= 0; + } + return result; +} + + +/* + Find the maximal key in a group that satisfies some range conditions for the + min/max argument field. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::next_max_in_range() + + DESCRIPTION + Given the sequence of ranges min_max_ranges, find the maximal key that is + in the right-most possible range. If there is no such key, then the current + group does not have a MAX key that satisfies the WHERE clause. If a key is + found, its value is stored in this->record. + + RETURN + 0 on success + HA_ERR_KEY_NOT_FOUND if there is no key with the given prefix in any of + the ranges + HA_ERR_END_OF_FILE - "" - + other if some error +*/ + +int QUICK_GROUP_MIN_MAX_SELECT::next_max_in_range() +{ + ha_rkey_function find_flag; + key_part_map keypart_map; + QUICK_RANGE *cur_range; + int result; + + DBUG_ASSERT(min_max_ranges.elements > 0); + + for (uint range_idx= min_max_ranges.elements; range_idx > 0; range_idx--) + { /* Search from the right-most range to the left. */ + get_dynamic(&min_max_ranges, (uchar*)&cur_range, range_idx - 1); + + /* + If the current value for the min/max argument is smaller than the left + boundary of cur_range, there is no need to check this range. + */ + if (range_idx != min_max_ranges.elements && + !(cur_range->flag & NO_MIN_RANGE) && + (key_cmp(min_max_arg_part, (const uchar*) cur_range->min_key, + min_max_arg_len) == -1)) + continue; + + if (cur_range->flag & NO_MAX_RANGE) + { + keypart_map= make_prev_keypart_map(real_key_parts); + find_flag= HA_READ_PREFIX_LAST; + } + else + { + /* Extend the search key with the upper boundary for this range. */ + memcpy(group_prefix + real_prefix_len, cur_range->max_key, + cur_range->max_length); + keypart_map= make_keypart_map(real_key_parts); + find_flag= (cur_range->flag & EQ_RANGE) ? + HA_READ_KEY_EXACT : (cur_range->flag & NEAR_MAX) ? + HA_READ_BEFORE_KEY : HA_READ_PREFIX_LAST_OR_PREV; + } + + result= file->ha_index_read_map(record, group_prefix, keypart_map, + find_flag); + + if (result) + { + if ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) && + (cur_range->flag & EQ_RANGE)) + continue; /* Check the next range. */ + + /* + In no key was found with this upper bound, there certainly are no keys + in the ranges to the left. + */ + return result; + } + /* A key was found. */ + if (cur_range->flag & EQ_RANGE) + return 0; /* No need to perform the checks below for equal keys. */ + + /* Check if record belongs to the current group. */ + if (key_cmp(index_info->key_part, group_prefix, real_prefix_len)) + continue; // Row not found + + /* If there is a lower limit, check if the found key is in the range. */ + if ( !(cur_range->flag & NO_MIN_RANGE) ) + { + int cmp_res= cmp_min_max_key(cur_range->min_key, cur_range->min_length); + /* + The key is outside of the range if: + the interval is open and the key is equal to the minimum boundry + or + the key is less than the minimum + */ + if (((cur_range->flag & NEAR_MIN) && cmp_res == 0) || + cmp_res < 0) + continue; + } + /* If we got to this point, the current key qualifies as MAX. */ + return result; + } + return HA_ERR_KEY_NOT_FOUND; +} + + +/* + Update all MIN function results with the newly found value. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::update_min_result() + + DESCRIPTION + The method iterates through all MIN functions and updates the result value + of each function by calling Item_sum::reset(), which in turn picks the new + result value from this->head->record[0], previously updated by + next_min(). The updated value is stored in a member variable of each of the + Item_sum objects, depending on the value type. + + IMPLEMENTATION + The update must be done separately for MIN and MAX, immediately after + next_min() was called and before next_max() is called, because both MIN and + MAX take their result value from the same buffer this->head->record[0] + (i.e. this->record). + + RETURN + None +*/ + +void QUICK_GROUP_MIN_MAX_SELECT::update_min_result() +{ + Item_sum *min_func; + + min_functions_it->rewind(); + while ((min_func= (*min_functions_it)++)) + min_func->reset_and_add(); +} + + +/* + Update all MAX function results with the newly found value. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::update_max_result() + + DESCRIPTION + The method iterates through all MAX functions and updates the result value + of each function by calling Item_sum::reset(), which in turn picks the new + result value from this->head->record[0], previously updated by + next_max(). The updated value is stored in a member variable of each of the + Item_sum objects, depending on the value type. + + IMPLEMENTATION + The update must be done separately for MIN and MAX, immediately after + next_max() was called, because both MIN and MAX take their result value + from the same buffer this->head->record[0] (i.e. this->record). + + RETURN + None +*/ + +void QUICK_GROUP_MIN_MAX_SELECT::update_max_result() +{ + Item_sum *max_func; + + max_functions_it->rewind(); + while ((max_func= (*max_functions_it)++)) + max_func->reset_and_add(); +} + + +/* + Append comma-separated list of keys this quick select uses to key_names; + append comma-separated list of corresponding used lengths to used_lengths. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::add_keys_and_lengths() + key_names [out] Names of used indexes + used_lengths [out] Corresponding lengths of the index names + + DESCRIPTION + This method is used by select_describe to extract the names of the + indexes used by a quick select. + +*/ + +void QUICK_GROUP_MIN_MAX_SELECT::add_keys_and_lengths(String *key_names, + String *used_lengths) +{ + bool first= TRUE; + + add_key_and_length(key_names, used_lengths, &first); +} + + +/* Check whether the number for equality ranges exceeds the set threshold */ + +bool eq_ranges_exceeds_limit(RANGE_SEQ_IF *seq, void *seq_init_param, + uint limit) +{ + KEY_MULTI_RANGE range; + range_seq_t seq_it; + uint count = 0; + + if (limit == 0) + { + /* 'Statistics instead of index dives' feature is turned off */ + return false; + } + seq_it= seq->init(seq_init_param, 0, 0); + while (!seq->next(seq_it, &range)) + { + if ((range.range_flag & EQ_RANGE) && !(range.range_flag & NULL_RANGE)) + { + if (++count >= limit) + return true; + } + } + return false; +} + +#ifndef DBUG_OFF + +static void print_sel_tree(PARAM *param, SEL_TREE *tree, key_map *tree_map, + const char *msg) +{ + char buff[1024]; + DBUG_ENTER("print_sel_tree"); + + String tmp(buff,sizeof(buff),&my_charset_bin); + tmp.length(0); + for (uint idx= 0; idx < param->keys; idx++) + { + if (tree_map->is_set(idx)) + { + uint keynr= param->real_keynr[idx]; + if (tmp.length()) + tmp.append(','); + tmp.append(¶m->table->key_info[keynr].name); + } + } + if (!tmp.length()) + tmp.append(STRING_WITH_LEN("(empty)")); + + DBUG_PRINT("info", ("SEL_TREE: %p (%s) scans: %s", tree, msg, + tmp.c_ptr_safe())); + + DBUG_VOID_RETURN; +} + + +static void print_ror_scans_arr(TABLE *table, const char *msg, + struct st_ror_scan_info **start, + struct st_ror_scan_info **end) +{ + DBUG_ENTER("print_ror_scans_arr"); + + char buff[1024]; + String tmp(buff,sizeof(buff),&my_charset_bin); + tmp.length(0); + for (;start != end; start++) + { + if (tmp.length()) + tmp.append(','); + tmp.append(&table->key_info[(*start)->keynr].name); + } + if (!tmp.length()) + tmp.append(STRING_WITH_LEN("(empty)")); + DBUG_PRINT("info", ("ROR key scans (%s): %s", msg, tmp.c_ptr())); + DBUG_VOID_RETURN; +} + +static String dbug_print_sel_arg_buf; + +static void +print_sel_arg_key(Field *field, const uchar *key, String *out) +{ + TABLE *table= field->table; + MY_BITMAP *old_sets[2]; + dbug_tmp_use_all_columns(table, old_sets, &table->read_set, &table->write_set); + + if (field->real_maybe_null()) + { + if (*key) + { + out->append("NULL"); + goto end; + } + key++; // Skip null byte + } + + field->set_key_image(key, field->pack_length()); + + if (field->type() == MYSQL_TYPE_BIT) + (void) field->val_int_as_str(out, 1); + else + field->val_str(out); + +end: + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); +} + + +/* + @brief + Produce a string representation of an individual SEL_ARG and return pointer + to it + + @detail + Intended usage: + + (gdb) p dbug_print_sel_arg(ptr) +*/ + +const char *dbug_print_sel_arg(SEL_ARG *sel_arg) +{ + StringBuffer<64> buf; + String &out= dbug_print_sel_arg_buf; + out.length(0); + + if (!sel_arg) + { + out.append("NULL"); + goto end; + } + + out.append("SEL_ARG("); + + const char *stype; + switch(sel_arg->type) { + case SEL_ARG::IMPOSSIBLE: + stype="IMPOSSIBLE"; + break; + case SEL_ARG::MAYBE: + stype="MAYBE"; + break; + case SEL_ARG::MAYBE_KEY: + stype="MAYBE_KEY"; + break; + case SEL_ARG::KEY_RANGE: + default: + stype= NULL; + } + + if (stype) + { + out.append("type="); + out.append(stype); + goto end; + } + + if (sel_arg->min_flag & NO_MIN_RANGE) + out.append("-inf"); + else + { + print_sel_arg_key(sel_arg->field, sel_arg->min_value, &buf); + out.append(buf); + } + + out.append((sel_arg->min_flag & NEAR_MIN)? "<" : "<="); + + out.append(sel_arg->field->field_name); + + out.append((sel_arg->max_flag & NEAR_MAX)? "<" : "<="); + + if (sel_arg->max_flag & NO_MAX_RANGE) + out.append("+inf"); + else + { + print_sel_arg_key(sel_arg->field, sel_arg->max_value, &buf); + out.append(buf); + } + + out.append(")"); + +end: + return dbug_print_sel_arg_buf.c_ptr_safe(); +} + + +/***************************************************************************** +** Print a quick range for debugging +** TODO: +** This should be changed to use a String to store each row instead +** of locking the DEBUG stream ! +*****************************************************************************/ + +static void +print_key(KEY_PART *key_part, const uchar *key, uint used_length) +{ + char buff[1024]; + const uchar *key_end= key+used_length; + uint store_length; + TABLE *table= key_part->field->table; + MY_BITMAP *old_sets[2]; + + dbug_tmp_use_all_columns(table, old_sets, &table->read_set, &table->write_set); + + for (; key < key_end; key+=store_length, key_part++) + { + String tmp(buff,sizeof(buff),&my_charset_bin); + Field *field= key_part->field; + store_length= key_part->store_length; + + if (field->real_maybe_null()) + { + if (*key) + { + fwrite("NULL",sizeof(char),4,DBUG_FILE); + continue; + } + key++; // Skip null byte + store_length--; + } + field->set_key_image(key, key_part->length); + if (field->type() == MYSQL_TYPE_BIT) + (void) field->val_int_as_str(&tmp, 1); + else + field->val_str(&tmp); + fwrite(tmp.ptr(),sizeof(char),tmp.length(),DBUG_FILE); + if (key+store_length < key_end) + fputc('/',DBUG_FILE); + } + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); +} + + +static void print_quick(QUICK_SELECT_I *quick, const key_map *needed_reg) +{ + char buf[MAX_KEY/8+1]; + TABLE *table; + MY_BITMAP *old_sets[2]; + DBUG_ENTER("print_quick"); + if (!quick) + DBUG_VOID_RETURN; + DBUG_LOCK_FILE; + + table= quick->head; + dbug_tmp_use_all_columns(table, old_sets, &table->read_set, &table->write_set); + quick->dbug_dump(0, TRUE); + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); + + fprintf(DBUG_FILE,"other_keys: 0x%s:\n", needed_reg->print(buf)); + + DBUG_UNLOCK_FILE; + DBUG_VOID_RETURN; +} + +void QUICK_RANGE_SELECT::dbug_dump(int indent, bool verbose) +{ + /* purecov: begin inspected */ + fprintf(DBUG_FILE, "%*squick range select, key %s, length: %d\n", + indent, "", head->key_info[index].name.str, max_used_key_length); + + if (verbose) + { + QUICK_RANGE *range; + QUICK_RANGE **pr= (QUICK_RANGE**)ranges.buffer; + QUICK_RANGE **end_range= pr + ranges.elements; + for (; pr != end_range; ++pr) + { + fprintf(DBUG_FILE, "%*s", indent + 2, ""); + range= *pr; + if (!(range->flag & NO_MIN_RANGE)) + { + print_key(key_parts, range->min_key, range->min_length); + if (range->flag & NEAR_MIN) + fputs(" < ",DBUG_FILE); + else + fputs(" <= ",DBUG_FILE); + } + fputs("X",DBUG_FILE); + + if (!(range->flag & NO_MAX_RANGE)) + { + if (range->flag & NEAR_MAX) + fputs(" < ",DBUG_FILE); + else + fputs(" <= ",DBUG_FILE); + print_key(key_parts, range->max_key, range->max_length); + } + fputs("\n",DBUG_FILE); + } + } + /* purecov: end */ +} + +void QUICK_INDEX_SORT_SELECT::dbug_dump(int indent, bool verbose) +{ + List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects); + QUICK_RANGE_SELECT *quick; + fprintf(DBUG_FILE, "%*squick index_merge select\n", indent, ""); + fprintf(DBUG_FILE, "%*smerged scans {\n", indent, ""); + while ((quick= it++)) + quick->dbug_dump(indent+2, verbose); + if (pk_quick_select) + { + fprintf(DBUG_FILE, "%*sclustered PK quick:\n", indent, ""); + pk_quick_select->dbug_dump(indent+2, verbose); + } + fprintf(DBUG_FILE, "%*s}\n", indent, ""); +} + +void QUICK_ROR_INTERSECT_SELECT::dbug_dump(int indent, bool verbose) +{ + List_iterator_fast<QUICK_SELECT_WITH_RECORD> it(quick_selects); + QUICK_SELECT_WITH_RECORD *qr; + fprintf(DBUG_FILE, "%*squick ROR-intersect select, %scovering\n", + indent, "", need_to_fetch_row? "":"non-"); + fprintf(DBUG_FILE, "%*smerged scans {\n", indent, ""); + while ((qr= it++)) + qr->quick->dbug_dump(indent+2, verbose); + if (cpk_quick) + { + fprintf(DBUG_FILE, "%*sclustered PK quick:\n", indent, ""); + cpk_quick->dbug_dump(indent+2, verbose); + } + fprintf(DBUG_FILE, "%*s}\n", indent, ""); +} + +void QUICK_ROR_UNION_SELECT::dbug_dump(int indent, bool verbose) +{ + List_iterator_fast<QUICK_SELECT_I> it(quick_selects); + QUICK_SELECT_I *quick; + fprintf(DBUG_FILE, "%*squick ROR-union select\n", indent, ""); + fprintf(DBUG_FILE, "%*smerged scans {\n", indent, ""); + while ((quick= it++)) + quick->dbug_dump(indent+2, verbose); + fprintf(DBUG_FILE, "%*s}\n", indent, ""); +} + + +/* + Print quick select information to DBUG_FILE. + + SYNOPSIS + QUICK_GROUP_MIN_MAX_SELECT::dbug_dump() + indent Indentation offset + verbose If TRUE show more detailed output. + + DESCRIPTION + Print the contents of this quick select to DBUG_FILE. The method also + calls dbug_dump() for the used quick select if any. + + IMPLEMENTATION + Caller is responsible for locking DBUG_FILE before this call and unlocking + it afterwards. + + RETURN + None +*/ + +void QUICK_GROUP_MIN_MAX_SELECT::dbug_dump(int indent, bool verbose) +{ + fprintf(DBUG_FILE, + "%*squick_group_min_max_select: index %s (%d), length: %d\n", + indent, "", index_info->name.str, index, max_used_key_length); + if (key_infix_len > 0) + { + fprintf(DBUG_FILE, "%*susing key_infix with length %d:\n", + indent, "", key_infix_len); + } + if (quick_prefix_select) + { + fprintf(DBUG_FILE, "%*susing quick_range_select:\n", indent, ""); + quick_prefix_select->dbug_dump(indent + 2, verbose); + } + if (min_max_ranges.elements > 0) + { + fprintf(DBUG_FILE, "%*susing %d quick_ranges for MIN/MAX:\n", + indent, "", min_max_ranges.elements); + } +} + +#endif /* !DBUG_OFF */ + + +/* + @brief Print the comparison operator for the min range +*/ + +static void print_min_range_operator(String *out, const ha_rkey_function flag) +{ + if (flag == HA_READ_AFTER_KEY) + out->append(STRING_WITH_LEN(" < ")); + else if (flag == HA_READ_KEY_EXACT || flag == HA_READ_KEY_OR_NEXT) + out->append(STRING_WITH_LEN(" <= ")); + else + out->append(STRING_WITH_LEN(" ? ")); +} + + +/* + @brief Print the comparison operator for the max range +*/ + +static void print_max_range_operator(String *out, const ha_rkey_function flag) +{ + if (flag == HA_READ_BEFORE_KEY) + out->append(STRING_WITH_LEN(" < ")); + else if (flag == HA_READ_AFTER_KEY) + out->append(STRING_WITH_LEN(" <= ")); + else + out->append(STRING_WITH_LEN(" ? ")); +} + + +static +void print_range(String *out, const KEY_PART_INFO *key_part, + KEY_MULTI_RANGE *range, uint n_key_parts) +{ + uint flag= range->range_flag; + String key_name; + key_name.set_charset(system_charset_info); + key_part_map keypart_map= range->start_key.keypart_map | + range->end_key.keypart_map; + + if (flag & GEOM_FLAG) + { + /* + The flags of GEOM ranges do not work the same way as for other + range types, so printing "col < some_geom" doesn't make sense. + Just print the column name, not operator. + */ + print_keyparts_name(out, key_part, n_key_parts, keypart_map); + out->append(STRING_WITH_LEN(" ")); + print_key_value(out, key_part, range->start_key.key, + range->start_key.length); + return; + } + + if (range->start_key.length) + { + print_key_value(out, key_part, range->start_key.key, + range->start_key.length); + print_min_range_operator(out, range->start_key.flag); + } + + print_keyparts_name(out, key_part, n_key_parts, keypart_map); + + if (range->end_key.length) + { + print_max_range_operator(out, range->end_key.flag); + print_key_value(out, key_part, range->end_key.key, + range->end_key.length); + } +} + + +/* + @brief Print range created for non-indexed columns + + @param + out output string + field field for which the range is printed + range range for the field +*/ + +static +void print_range_for_non_indexed_field(String *out, Field *field, + KEY_MULTI_RANGE *range) +{ + TABLE *table= field->table; + MY_BITMAP *old_sets[2]; + dbug_tmp_use_all_columns(table, old_sets, &table->read_set, &table->write_set); + + if (range->start_key.length) + { + field->print_key_part_value(out, range->start_key.key, field->key_length()); + print_min_range_operator(out, range->start_key.flag); + } + + out->append(field->field_name); + + if (range->end_key.length) + { + print_max_range_operator(out, range->end_key.flag); + field->print_key_part_value(out, range->end_key.key, field->key_length()); + } + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); +} + + + +/* + + Add ranges to the trace + For ex: + lets say we have an index a_b(a,b) + query: select * from t1 where a=2 and b=4 ; + so we create a range: + (2,4) <= (a,b) <= (2,4) + this is added to the trace +*/ + +static void trace_ranges(Json_writer_array *range_trace, + PARAM *param, uint idx, + SEL_ARG *keypart, + const KEY_PART_INFO *key_parts) +{ + SEL_ARG_RANGE_SEQ seq; + KEY_MULTI_RANGE range; + range_seq_t seq_it; + uint flags= 0; + RANGE_SEQ_IF seq_if = {NULL, sel_arg_range_seq_init, + sel_arg_range_seq_next, 0, 0}; + KEY *keyinfo= param->table->key_info + param->real_keynr[idx]; + uint n_key_parts= param->table->actual_n_key_parts(keyinfo); + DBUG_ASSERT(range_trace->trace_started()); + seq.keyno= idx; + seq.real_keyno= param->real_keynr[idx]; + seq.param= param; + seq.start= keypart; + /* + is_ror_scan is set to FALSE here, because we are only interested + in iterating over all the ranges and printing them. + */ + seq.is_ror_scan= FALSE; + const KEY_PART_INFO *cur_key_part= key_parts + keypart->part; + seq_it= seq_if.init((void *) &seq, 0, flags); + + while (!seq_if.next(seq_it, &range)) + { + StringBuffer<128> range_info(system_charset_info); + print_range(&range_info, cur_key_part, &range, n_key_parts); + range_trace->add(range_info.c_ptr_safe(), range_info.length()); + } +} + +/** + Print a key to a string + + @param[out] out String the key is appended to + @param[in] key_part Index components description + @param[in] key Key tuple + @param[in] used_length length of the key tuple +*/ + +static void print_key_value(String *out, const KEY_PART_INFO *key_part, + const uchar* key, uint used_length) +{ + out->append(STRING_WITH_LEN("(")); + Field *field= key_part->field; + StringBuffer<128> tmp(system_charset_info); + TABLE *table= field->table; + uint store_length; + MY_BITMAP *old_sets[2]; + dbug_tmp_use_all_columns(table, old_sets, &table->read_set, &table->write_set); + const uchar *key_end= key+used_length; + + for (; key < key_end; key+=store_length, key_part++) + { + field= key_part->field; + store_length= key_part->store_length; + + field->print_key_part_value(out, key, key_part->length); + + if (key + store_length < key_end) + out->append(STRING_WITH_LEN(",")); + } + dbug_tmp_restore_column_maps(&table->read_set, &table->write_set, old_sets); + out->append(STRING_WITH_LEN(")")); +} + +/** + Print key parts involed in a range + @param[out] out String the key is appended to + @param[in] key_part Index components description + @param[in] n_keypart Number of keyparts in index + @param[in] keypart_map map for keyparts involved in the range +*/ + +void print_keyparts_name(String *out, const KEY_PART_INFO *key_part, + uint n_keypart, key_part_map keypart_map) +{ + uint i; + out->append(STRING_WITH_LEN("(")); + bool first_keypart= TRUE; + for (i=0; i < n_keypart; key_part++, i++) + { + if (keypart_map & (1 << i)) + { + if (first_keypart) + first_keypart= FALSE; + else + out->append(STRING_WITH_LEN(",")); + out->append(key_part->field->field_name); + } + else + break; + } + out->append(STRING_WITH_LEN(")")); +} |