diff options
Diffstat (limited to '')
| -rw-r--r-- | sql/sql_join_cache.h | 1455 |
1 files changed, 1455 insertions, 0 deletions
diff --git a/sql/sql_join_cache.h b/sql/sql_join_cache.h new file mode 100644 index 00000000..d2d2e1a1 --- /dev/null +++ b/sql/sql_join_cache.h @@ -0,0 +1,1455 @@ +/* + Copyright (c) 2011, 2012, Monty Program Ab + + 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 Street, Fifth Floor, Boston, MA 02110-1335 USA */ + +/* + This file contains declarations for implementations + of block based join algorithms +*/ + +#define JOIN_CACHE_INCREMENTAL_BIT 1 +#define JOIN_CACHE_HASHED_BIT 2 +#define JOIN_CACHE_BKA_BIT 4 + +/* + Categories of data fields of variable length written into join cache buffers. + The value of any of these fields is written into cache together with the + prepended length of the value. +*/ +#define CACHE_BLOB 1 /* blob field */ +#define CACHE_STRIPPED 2 /* field stripped of trailing spaces */ +#define CACHE_VARSTR1 3 /* short string value (length takes 1 byte) */ +#define CACHE_VARSTR2 4 /* long string value (length takes 2 bytes) */ +#define CACHE_ROWID 5 /* ROWID field */ + +/* + The CACHE_FIELD structure used to describe fields of records that + are written into a join cache buffer from record buffers and backward. +*/ +typedef struct st_cache_field { + uchar *str; /**< buffer from/to where the field is to be copied */ + uint length; /**< maximal number of bytes to be copied from/to str */ + /* + Field object for the moved field + (0 - for a flag field, see JOIN_CACHE::create_flag_fields). + */ + Field *field; + uint type; /**< category of the of the copied field (CACHE_BLOB et al.) */ + /* + The number of the record offset value for the field in the sequence + of offsets placed after the last field of the record. These + offset values are used to access fields referred to from other caches. + If the value is 0 then no offset for the field is saved in the + trailing sequence of offsets. + */ + uint referenced_field_no; + /* The remaining structure fields are used as containers for temp values */ + uint blob_length; /**< length of the blob to be copied */ + uint offset; /**< field offset to be saved in cache buffer */ +} CACHE_FIELD; + + +class JOIN_TAB_SCAN; + +class EXPLAIN_BKA_TYPE; + +/* + JOIN_CACHE is the base class to support the implementations of + - Block Nested Loop (BNL) Join Algorithm, + - Block Nested Loop Hash (BNLH) Join Algorithm, + - Batched Key Access (BKA) Join Algorithm. + + The first algorithm is supported by the derived class JOIN_CACHE_BNL, + the second algorithm is supported by the derived class JOIN_CACHE_BNLH, + while the third algorithm is implemented in two variant supported by + the classes JOIN_CACHE_BKA and JOIN_CACHE_BKAH. + These three algorithms have a lot in common. Each of them first accumulates + the records of the left join operand in a join buffer and then searches for + matching rows of the second operand for all accumulated records. + For the first two algorithms this strategy saves on logical I/O operations: + the entire set of records from the join buffer requires only one look-through + of the records provided by the second operand. + For the third algorithm the accumulation of records allows to optimize + fetching rows of the second operand from disk for some engines (MyISAM, + InnoDB), or to minimize the number of round-trips between the Server and + the engine nodes. +*/ + +class JOIN_CACHE :public Sql_alloc +{ + +private: + + /* Size of the offset of a record from the cache */ + uint size_of_rec_ofs; + /* Size of the length of a record in the cache */ + uint size_of_rec_len; + /* Size of the offset of a field within a record in the cache */ + uint size_of_fld_ofs; + + /* This structure is used only for explain, not for execution */ + bool for_explain_only; + +protected: + + /* 3 functions below actually do not use the hidden parameter 'this' */ + + /* Calculate the number of bytes used to store an offset value */ + uint offset_size(size_t len) + { return (len < 256 ? 1 : len < 256*256 ? 2 : 4); } + + /* Get the offset value that takes ofs_sz bytes at the position ptr */ + ulong get_offset(uint ofs_sz, uchar *ptr) + { + switch (ofs_sz) { + case 1: return uint(*ptr); + case 2: return uint2korr(ptr); + case 4: return uint4korr(ptr); + } + return 0; + } + + /* Set the offset value ofs that takes ofs_sz bytes at the position ptr */ + void store_offset(uint ofs_sz, uchar *ptr, ulong ofs) + { + switch (ofs_sz) { + case 1: *ptr= (uchar) ofs; return; + case 2: int2store(ptr, (uint16) ofs); return; + case 4: int4store(ptr, (uint32) ofs); return; + } + } + size_t calc_avg_record_length(); + + /* + The maximum total length of the fields stored for a record in the cache. + For blob fields only the sizes of the blob lengths are taken into account. + */ + uint length; + + /* + Representation of the executed multi-way join through which all needed + context can be accessed. + */ + JOIN *join; + + /* + JOIN_TAB of the first table that can have it's fields in the join cache. + That is, tables in the [start_tab, tab) range can have their fields in the + join cache. + If a join tab in the range represents an SJM-nest, then all tables from the + nest can have their fields in the join cache, too. + */ + JOIN_TAB *start_tab; + + /* + The total number of flag and data fields that can appear in a record + written into the cache. Fields with null values are always skipped + to save space. + */ + uint fields; + + /* + The total number of flag fields in a record put into the cache. They are + used for table null bitmaps, table null row flags, and an optional match + flag. Flag fields go before other fields in a cache record with the match + flag field placed always at the very beginning of the record. + */ + uint flag_fields; + + /* The total number of blob fields that are written into the cache */ + uint blobs; + + /* + The total number of fields referenced from field descriptors for other join + caches. These fields are used to construct key values. + When BKA join algorithm is employed the constructed key values serve to + access matching rows with index lookups. + The key values are put into a hash table when the BNLH join algorithm + is employed and when BKAH is used for the join operation. + */ + uint referenced_fields; + + /* + The current number of already created data field descriptors. + This number can be useful for implementations of the init methods. + */ + uint data_field_count; + + /* + The current number of already created pointers to the data field + descriptors. This number can be useful for implementations of + the init methods. + */ + uint data_field_ptr_count; + + /* + Array of the descriptors of fields containing 'fields' elements. + These are all fields that are stored for a record in the cache. + */ + CACHE_FIELD *field_descr; + + /* + Array of pointers to the blob descriptors that contains 'blobs' elements. + */ + CACHE_FIELD **blob_ptr; + + /* + This flag indicates that records written into the join buffer contain + a match flag field. + This is set to true for the first inner table of an outer join or a + semi-join. + The flag must be set by the init method. + Currently any implementation of the virtial init method calls + the function JOIN_CACHE::calc_record_fields() to set this flag. + */ + bool with_match_flag; + /* + This flag indicates that any record is prepended with the length of the + record which allows us to skip the record or part of it without reading. + */ + bool with_length; + + /* + The maximal number of bytes used for a record representation in + the cache excluding the space for blob data. + For future derived classes this representation may contains some + redundant info such as a key value associated with the record. + */ + uint pack_length; + /* + The value of pack_length incremented by the total size of all + pointers of a record in the cache to the blob data. + */ + uint pack_length_with_blob_ptrs; + + /* + The total size of the record base prefix. The base prefix of record may + include the following components: + - the length of the record + - the link to a record in a previous buffer. + Each record in the buffer are supplied with the same set of the components. + */ + uint base_prefix_length; + + /* + The expected length of a record in the join buffer together with + all prefixes and postfixes + */ + size_t avg_record_length; + + /* The expected size of the space per record in the auxiliary buffer */ + size_t avg_aux_buffer_incr; + + /* Pointer to the beginning of the join buffer */ + uchar *buff; + /* + Size of the entire memory allocated for the join buffer. + Part of this memory may be reserved for the auxiliary buffer. + */ + size_t buff_size; + /* The minimal join buffer size when join buffer still makes sense to use */ + size_t min_buff_size; + /* The maximum expected size if the join buffer to be used */ + size_t max_buff_size; + /* Size of the auxiliary buffer */ + size_t aux_buff_size; + + /* The number of records put into the join buffer */ + size_t records; + /* + The number of records in the fully refilled join buffer of + the minimal size equal to min_buff_size + */ + size_t min_records; + + /* + Pointer to the current position in the join buffer. + This member is used both when writing to buffer and + when reading from it. + */ + uchar *pos; + /* + Pointer to the first free position in the join buffer, + right after the last record into it. + */ + uchar *end_pos; + + /* + Pointer to the beginning of the first field of the current read/write + record from the join buffer. The value is adjusted by the + get_record/put_record functions. + */ + uchar *curr_rec_pos; + /* + Pointer to the beginning of the first field of the last record + from the join buffer. + */ + uchar *last_rec_pos; + + /* + Flag is set if the blob data for the last record in the join buffer + is in record buffers rather than in the join cache. + */ + bool last_rec_blob_data_is_in_rec_buff; + + /* + Pointer to the position to the current record link. + Record links are used only with linked caches. Record links allow to set + connections between parts of one join record that are stored in different + join buffers. + In the simplest case a record link is just a pointer to the beginning of + the record stored in the buffer. + In a more general case a link could be a reference to an array of pointers + to records in the buffer. + */ + uchar *curr_rec_link; + + /* + This flag is set to TRUE if join_tab is the first inner table of an outer + join and the latest record written to the join buffer is detected to be + null complemented after checking on conditions over the outer tables for + this outer join operation + */ + bool last_written_is_null_compl; + + /* + The number of fields put in the join buffer of the join cache that are + used in building keys to access the table join_tab + */ + uint local_key_arg_fields; + /* + The total number of the fields in the previous caches that are used + in building keys to access the table join_tab + */ + uint external_key_arg_fields; + + /* + This flag indicates that the key values will be read directly from the join + buffer. It will save us building key values in the key buffer. + */ + bool use_emb_key; + /* The length of an embedded key value */ + uint emb_key_length; + + /* This flag is used only when 'not exists' optimization can be applied */ + bool not_exists_opt_is_applicable; + + /* + This object provides the methods to iterate over records of + the joined table join_tab when looking for join matches between + records from join buffer and records from join_tab. + BNL and BNLH join algorithms retrieve all records from join_tab, + while BKA/BKAH algorithm iterates only over those records from + join_tab that can be accessed by look-ups with join keys built + from records in join buffer. + */ + JOIN_TAB_SCAN *join_tab_scan; + + void calc_record_fields(); + void collect_info_on_key_args(); + int alloc_fields(); + void create_flag_fields(); + void create_key_arg_fields(); + void create_remaining_fields(); + void set_constants(); + int alloc_buffer(); + + /* Shall reallocate the join buffer */ + virtual int realloc_buffer(); + + /* Check the possibility to read the access keys directly from join buffer */ + bool check_emb_key_usage(); + + uint get_size_of_rec_offset() { return size_of_rec_ofs; } + uint get_size_of_rec_length() { return size_of_rec_len; } + uint get_size_of_fld_offset() { return size_of_fld_ofs; } + + uchar *get_rec_ref(uchar *ptr) + { + return buff+get_offset(size_of_rec_ofs, ptr-size_of_rec_ofs); + } + ulong get_rec_length(uchar *ptr) + { + return (ulong) get_offset(size_of_rec_len, ptr); + } + ulong get_fld_offset(uchar *ptr) + { + return (ulong) get_offset(size_of_fld_ofs, ptr); + } + + void store_rec_ref(uchar *ptr, uchar* ref) + { + store_offset(size_of_rec_ofs, ptr-size_of_rec_ofs, (ulong) (ref-buff)); + } + void store_rec_length(uchar *ptr, ulong len) + { + store_offset(size_of_rec_len, ptr, len); + } + void store_fld_offset(uchar *ptr, ulong ofs) + { + store_offset(size_of_fld_ofs, ptr, ofs); + } + + /* Write record fields and their required offsets into the join buffer */ + uint write_record_data(uchar *link, bool *is_full); + + /* Get the total length of all prefixes of a record in the join buffer */ + virtual uint get_prefix_length() { return base_prefix_length; } + /* Get maximum total length of all affixes of a record in the join buffer */ + virtual uint get_record_max_affix_length(); + + /* + Shall get maximum size of the additional space per record used for + record keys + */ + virtual uint get_max_key_addon_space_per_record() { return 0; } + + /* + This method must determine for how much the auxiliary buffer should be + incremented when a new record is added to the join buffer. + If no auxiliary buffer is needed the function should return 0. + */ + virtual uint aux_buffer_incr(size_t recno); + + /* Shall calculate how much space is remaining in the join buffer */ + virtual size_t rem_space() + { + return MY_MAX(buff_size-(end_pos-buff)-aux_buff_size,0); + } + + /* + Shall calculate how much space is taken by allocation of the key + for a record in the join buffer + */ + virtual uint extra_key_length() { return 0; } + + /* Read all flag and data fields of a record from the join buffer */ + uint read_all_record_fields(); + + /* Read all flag fields of a record from the join buffer */ + uint read_flag_fields(); + + /* Read a data record field from the join buffer */ + uint read_record_field(CACHE_FIELD *copy, bool last_record); + + /* Read a referenced field from the join buffer */ + bool read_referenced_field(CACHE_FIELD *copy, uchar *rec_ptr, uint *len); + + /* + Shall skip record from the join buffer if its match flag + is set to MATCH_FOUND + */ + virtual bool skip_if_matched(); + + /* + Shall skip record from the join buffer if its match flag + commands to do so + */ + virtual bool skip_if_not_needed_match(); + + /* + True if rec_ptr points to the record whose blob data stay in + record buffers + */ + bool blob_data_is_in_rec_buff(uchar *rec_ptr) + { + return rec_ptr == last_rec_pos && last_rec_blob_data_is_in_rec_buff; + } + + /* Find matches from the next table for records from the join buffer */ + virtual enum_nested_loop_state join_matching_records(bool skip_last); + + /* Shall set an auxiliary buffer up (currently used only by BKA joins) */ + virtual int setup_aux_buffer(HANDLER_BUFFER &aux_buff) + { + DBUG_ASSERT(0); + return 0; + } + + /* + Shall get the number of ranges in the cache buffer passed + to the MRR interface + */ + virtual uint get_number_of_ranges_for_mrr() { return 0; }; + + /* + Shall prepare to look for records from the join cache buffer that would + match the record of the joined table read into the record buffer + */ + virtual bool prepare_look_for_matches(bool skip_last)= 0; + /* + Shall return a pointer to the record from join buffer that is checked + as the next candidate for a match with the current record from join_tab. + Each implementation of this virtual function should bare in mind + that the record position it returns shall be exactly the position + passed as the parameter to the implementations of the virtual functions + skip_next_candidate_for_match and read_next_candidate_for_match. + */ + virtual uchar *get_next_candidate_for_match()= 0; + /* + Shall check whether the given record from the join buffer has its match + flag settings commands to skip the record in the buffer. + */ + virtual bool skip_next_candidate_for_match(uchar *rec_ptr)= 0; + /* + Shall read the given record from the join buffer into the + the corresponding record buffer + */ + virtual void read_next_candidate_for_match(uchar *rec_ptr)= 0; + + /* + Shall return the location of the association label returned by + the multi_read_range_next function for the current record loaded + into join_tab's record buffer + */ + virtual uchar **get_curr_association_ptr() { return 0; }; + + /* Add null complements for unmatched outer records from the join buffer */ + virtual enum_nested_loop_state join_null_complements(bool skip_last); + + /* Restore the fields of the last record from the join buffer */ + virtual void restore_last_record(); + + /* Set match flag for a record in join buffer if it has not been set yet */ + bool set_match_flag_if_none(JOIN_TAB *first_inner, uchar *rec_ptr); + + enum_nested_loop_state generate_full_extensions(uchar *rec_ptr); + + /* Check matching to a partial join record from the join buffer */ + bool check_match(uchar *rec_ptr); + + /* + This constructor creates an unlinked join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + */ + JOIN_CACHE(JOIN *j, JOIN_TAB *tab) + { + join= j; + join_tab= tab; + prev_cache= next_cache= 0; + buff= 0; + min_buff_size= max_buff_size= 0; // Caches + not_exists_opt_is_applicable= false; + } + + /* + This constructor creates a linked join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + */ + JOIN_CACHE(JOIN *j, JOIN_TAB *tab, JOIN_CACHE *prev) + { + join= j; + join_tab= tab; + next_cache= 0; + prev_cache= prev; + buff= 0; + min_buff_size= max_buff_size= 0; // Caches + if (prev) + prev->next_cache= this; + } + +public: + + /* + The enumeration type Join_algorithm includes a mnemonic constant for + each join algorithm that employs join buffers + */ + + enum Join_algorithm + { + BNL_JOIN_ALG, /* Block Nested Loop Join algorithm */ + BNLH_JOIN_ALG, /* Block Nested Loop Hash Join algorithm */ + BKA_JOIN_ALG, /* Batched Key Access Join algorithm */ + BKAH_JOIN_ALG /* Batched Key Access with Hash Table Join Algorithm */ + }; + + /* + The enumeration type Match_flag describes possible states of the match flag + field stored for the records of the first inner tables of outer joins and + semi-joins in the cases when the first match strategy is used for them. + When a record with match flag field is written into the join buffer the + state of the field usually is MATCH_NOT_FOUND unless this is a record of the + first inner table of the outer join for which the on precondition (the + condition from on expression over outer tables) has turned out not to be + true. In the last case the state of the match flag is MATCH_IMPOSSIBLE. + The state of the match flag field is changed to MATCH_FOUND as soon as + the first full matching combination of inner tables of the outer join or + the semi-join is discovered. + */ + enum Match_flag { MATCH_NOT_FOUND, MATCH_FOUND, MATCH_IMPOSSIBLE }; + + /* Table to be joined with the partial join records from the cache */ + JOIN_TAB *join_tab; + + /* Pointer to the previous join cache if there is any */ + JOIN_CACHE *prev_cache; + /* Pointer to the next join cache if there is any */ + JOIN_CACHE *next_cache; + + /* Shall initialize the join cache structure */ + virtual int init(bool for_explain); + + /* Get the current size of the cache join buffer */ + size_t get_join_buffer_size() { return buff_size; } + /* Set the size of the cache join buffer to a new value */ + void set_join_buffer_size(size_t sz) { buff_size= sz; } + + /* Get the minimum possible size of the cache join buffer */ + size_t get_min_join_buffer_size(); + /* Get the maximum possible size of the cache join buffer */ + size_t get_max_join_buffer_size(bool optimize_buff_size, + size_t min_buffer_size_arg); + + /* Shrink the size if the cache join buffer in a given ratio */ + bool shrink_join_buffer_in_ratio(ulonglong n, ulonglong d); + + /* Shall return the type of the employed join algorithm */ + virtual enum Join_algorithm get_join_alg()= 0; + + /* + The function shall return TRUE only when there is a key access + to the join table + */ + virtual bool is_key_access()= 0; + + /* Shall reset the join buffer for reading/writing */ + virtual void reset(bool for_writing); + + /* + This function shall add a record into the join buffer and return TRUE + if it has been decided that it should be the last record in the buffer. + */ + virtual bool put_record(); + + /* + This function shall read the next record into the join buffer and return + TRUE if there is no more next records. + */ + virtual bool get_record(); + + /* + This function shall read the record at the position rec_ptr + in the join buffer + */ + virtual void get_record_by_pos(uchar *rec_ptr); + + /* Shall return the value of the match flag for the positioned record */ + virtual enum Match_flag get_match_flag_by_pos(uchar *rec_ptr); + + /* + Shall return the value of the match flag for the positioned record + from the join buffer attached to the specified table + */ + virtual enum Match_flag + get_match_flag_by_pos_from_join_buffer(uchar *rec_ptr, JOIN_TAB *tab); + + /* Shall return the position of the current record */ + virtual uchar *get_curr_rec() { return curr_rec_pos; } + + /* Shall set the current record link */ + virtual void set_curr_rec_link(uchar *link) { curr_rec_link= link; } + + /* Shall return the current record link */ + virtual uchar *get_curr_rec_link() + { + return (curr_rec_link ? curr_rec_link : get_curr_rec()); + } + + /* Join records from the join buffer with records from the next join table */ + enum_nested_loop_state join_records(bool skip_last); + + /* Add a comment on the join algorithm employed by the join cache */ + virtual bool save_explain_data(EXPLAIN_BKA_TYPE *explain); + + THD *thd(); + + virtual ~JOIN_CACHE() = default; + void reset_join(JOIN *j) { join= j; } + void free() + { + my_free(buff); + buff= 0; + } + + friend class JOIN_CACHE_HASHED; + friend class JOIN_CACHE_BNL; + friend class JOIN_CACHE_BKA; + friend class JOIN_TAB_SCAN; + friend class JOIN_TAB_SCAN_MRR; + +}; + + +/* + The class JOIN_CACHE_HASHED is the base class for the classes + JOIN_CACHE_HASHED_BNL and JOIN_CACHE_HASHED_BKA. The first of them supports + an implementation of Block Nested Loop Hash (BNLH) Join Algorithm, + while the second is used for a variant of the BKA Join algorithm that performs + only one lookup for any records from join buffer with the same key value. + For a join cache of this class the records from the join buffer that have + the same access key are linked into a chain attached to a key entry structure + that either itself contains the key value, or, in the case when the keys are + embedded, refers to its occurrence in one of the records from the chain. + To build the chains with the same keys a hash table is employed. It is placed + at the very end of the join buffer. The array of hash entries is allocated + first at the very bottom of the join buffer, while key entries are placed + before this array. + A hash entry contains a header of the list of the key entries with the same + hash value. + Each key entry is a structure of the following type: + struct st_join_cache_key_entry { + union { + uchar[] value; + cache_ref *value_ref; // offset from the beginning of the buffer + } hash_table_key; + key_ref next_key; // offset backward from the beginning of hash table + cache_ref *last_rec // offset from the beginning of the buffer + } + The references linking the records in a chain are always placed at the very + beginning of the record info stored in the join buffer. The records are + linked in a circular list. A new record is always added to the end of this + list. + + The following picture represents a typical layout for the info stored in the + join buffer of a join cache object of the JOIN_CACHE_HASHED class. + + buff + V + +----------------------------------------------------------------------------+ + | |[*]record_1_1| | + | ^ | | + | | +--------------------------------------------------+ | + | | |[*]record_2_1| | | + | | ^ | V | + | | | +------------------+ |[*]record_1_2| | + | | +--------------------+-+ | | + |+--+ +---------------------+ | | +-------------+ | + || | | V | | | + |||[*]record_3_1| |[*]record_1_3| |[*]record_2_2| | | + ||^ ^ ^ | | + ||+----------+ | | | | + ||^ | |<---------------------------+-------------------+ | + |++ | | ... mrr | buffer ... ... | | | + | | | | | + | +-----+--------+ | +-----|-------+ | + | V | | | V | | | + ||key_3|[/]|[*]| | | |key_2|[/]|[*]| | | + | +-+---|-----------------------+ | | + | V | | | | | + | |key_1|[*]|[*]| | | ... |[*]| ... |[*]| ... | | + +----------------------------------------------------------------------------+ + ^ ^ ^ + | i-th entry j-th entry + hash table + + i-th hash entry: + circular record chain for key_1: + record_1_1 + record_1_2 + record_1_3 (points to record_1_1) + circular record chain for key_3: + record_3_1 (points to itself) + + j-th hash entry: + circular record chain for key_2: + record_2_1 + record_2_2 (points to record_2_1) + +*/ + +class JOIN_CACHE_HASHED: public JOIN_CACHE +{ + + typedef uint (JOIN_CACHE_HASHED::*Hash_func) (uchar *key, uint key_len); + typedef bool (JOIN_CACHE_HASHED::*Hash_cmp_func) (uchar *key1, uchar *key2, + uint key_len); + +private: + + /* Size of the offset of a key entry in the hash table */ + uint size_of_key_ofs; + + /* + Length of the key entry in the hash table. + A key entry either contains the key value, or it contains a reference + to the key value if use_emb_key flag is set for the cache. + */ + uint key_entry_length; + + /* The beginning of the hash table in the join buffer */ + uchar *hash_table; + /* Number of hash entries in the hash table */ + uint hash_entries; + + + /* The position of the currently retrieved key entry in the hash table */ + uchar *curr_key_entry; + + /* The offset of the data fields from the beginning of the record fields */ + uint data_fields_offset; + + inline uint get_hash_idx_simple(uchar *key, uint key_len); + inline uint get_hash_idx_complex(uchar *key, uint key_len); + + inline bool equal_keys_simple(uchar *key1, uchar *key2, uint key_len); + inline bool equal_keys_complex(uchar *key1, uchar *key2, uint key_len); + + int init_hash_table(); + void cleanup_hash_table(); + +protected: + + /* + Index info on the TABLE_REF object used by the hash join + to look for matching records + */ + KEY *ref_key_info; + /* + Number of the key parts the TABLE_REF object used by the hash join + to look for matching records + */ + uint ref_used_key_parts; + + /* + The hash function used in the hash table, + usually set by the init() method + */ + Hash_func hash_func; + /* + The function to check whether two key entries in the hash table + are equal or not, usually set by the init() method + */ + Hash_cmp_func hash_cmp_func; + + /* + Length of a key value. + It is assumed that all key values have the same length. + */ + uint key_length; + /* Buffer to store key values for probing */ + uchar *key_buff; + + /* Number of key entries in the hash table (number of distinct keys) */ + uint key_entries; + + /* The position of the last key entry in the hash table */ + uchar *last_key_entry; + + /* + The offset of the record fields from the beginning of the record + representation. The record representation starts with a reference to + the next record in the key record chain followed by the length of + the trailing record data followed by a reference to the record segment + in the previous cache, if any, followed by the record fields. + */ + uint rec_fields_offset; + + uint get_size_of_key_offset() { return size_of_key_ofs; } + + /* + Get the position of the next_key_ptr field pointed to by + a linking reference stored at the position key_ref_ptr. + This reference is actually the offset backward from the + beginning of hash table. + */ + uchar *get_next_key_ref(uchar *key_ref_ptr) + { + return hash_table-get_offset(size_of_key_ofs, key_ref_ptr); + } + + /* + Store the linking reference to the next_key_ptr field at + the position key_ref_ptr. The position of the next_key_ptr + field is pointed to by ref. The stored reference is actually + the offset backward from the beginning of the hash table. + */ + void store_next_key_ref(uchar *key_ref_ptr, uchar *ref) + { + store_offset(size_of_key_ofs, key_ref_ptr, (ulong) (hash_table-ref)); + } + + /* + Check whether the reference to the next_key_ptr field at the position + key_ref_ptr contains a nil value. + */ + bool is_null_key_ref(uchar *key_ref_ptr) + { + ulong nil= 0; + return memcmp(key_ref_ptr, &nil, size_of_key_ofs ) == 0; + } + + /* + Set the reference to the next_key_ptr field at the position + key_ref_ptr equal to nil. + */ + void store_null_key_ref(uchar *key_ref_ptr) + { + ulong nil= 0; + store_offset(size_of_key_ofs, key_ref_ptr, nil); + } + + uchar *get_next_rec_ref(uchar *ref_ptr) + { + return buff+get_offset(get_size_of_rec_offset(), ref_ptr); + } + + void store_next_rec_ref(uchar *ref_ptr, uchar *ref) + { + store_offset(get_size_of_rec_offset(), ref_ptr, (ulong) (ref-buff)); + } + + /* + Get the position of the embedded key value for the current + record pointed to by get_curr_rec(). + */ + uchar *get_curr_emb_key() + { + return get_curr_rec()+data_fields_offset; + } + + /* + Get the position of the embedded key value pointed to by a reference + stored at ref_ptr. The stored reference is actually the offset from + the beginning of the join buffer. + */ + uchar *get_emb_key(uchar *ref_ptr) + { + return buff+get_offset(get_size_of_rec_offset(), ref_ptr); + } + + /* + Store the reference to an embedded key at the position key_ref_ptr. + The position of the embedded key is pointed to by ref. The stored + reference is actually the offset from the beginning of the join buffer. + */ + void store_emb_key_ref(uchar *ref_ptr, uchar *ref) + { + store_offset(get_size_of_rec_offset(), ref_ptr, (ulong) (ref-buff)); + } + + /* Get the total length of all prefixes of a record in hashed join buffer */ + uint get_prefix_length() + { + return base_prefix_length + get_size_of_rec_offset(); + } + + /* + Get maximum size of the additional space per record used for + the hash table with record keys + */ + uint get_max_key_addon_space_per_record(); + + /* + Calculate how much space in the buffer would not be occupied by + records, key entries and additional memory for the MMR buffer. + */ + size_t rem_space() + { + return MY_MAX(last_key_entry-end_pos-aux_buff_size,0); + } + + /* + Calculate how much space is taken by allocation of the key + entry for a record in the join buffer + */ + uint extra_key_length() { return key_entry_length; } + + /* + Skip record from a hashed join buffer if its match flag + is set to MATCH_FOUND + */ + bool skip_if_matched(); + + /* + Skip record from a hashed join buffer if its match flag setting + commands to do so + */ + bool skip_if_not_needed_match(); + + /* Search for a key in the hash table of the join buffer */ + bool key_search(uchar *key, uint key_len, uchar **key_ref_ptr); + + /* Reallocate the join buffer of a hashed join cache */ + int realloc_buffer(); + + /* + This constructor creates an unlinked hashed join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + */ + JOIN_CACHE_HASHED(JOIN *j, JOIN_TAB *tab) :JOIN_CACHE(j, tab) {} + + /* + This constructor creates a linked hashed join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + */ + JOIN_CACHE_HASHED(JOIN *j, JOIN_TAB *tab, JOIN_CACHE *prev) + :JOIN_CACHE(j, tab, prev) {} + +public: + + /* Initialize a hashed join cache */ + int init(bool for_explain); + + /* Reset the buffer of a hashed join cache for reading/writing */ + void reset(bool for_writing); + + /* Add a record into the buffer of a hashed join cache */ + bool put_record(); + + /* Read the next record from the buffer of a hashed join cache */ + bool get_record(); + + /* + Shall check whether all records in a key chain have + their match flags set on + */ + virtual bool check_all_match_flags_for_key(uchar *key_chain_ptr); + + uint get_next_key(uchar **key); + + /* Get the head of the record chain attached to the current key entry */ + uchar *get_curr_key_chain() + { + return get_next_rec_ref(curr_key_entry+key_entry_length- + get_size_of_rec_offset()); + } + +}; + + +/* + The class JOIN_TAB_SCAN is a companion class for the classes JOIN_CACHE_BNL + and JOIN_CACHE_BNLH. Actually the class implements the iterator over the + table joinded by BNL/BNLH join algorithm. + The virtual functions open, next and close are called for any iteration over + the table. The function open is called to initiate the process of the + iteration. The function next shall read the next record from the joined + table. The record is read into the record buffer of the joined table. + The record is to be matched with records from the join cache buffer. + The function close shall perform the finalizing actions for the iteration. +*/ + +class JOIN_TAB_SCAN: public Sql_alloc +{ + +private: + /* TRUE if this is the first record from the joined table to iterate over */ + bool is_first_record; + +protected: + + /* The joined table to be iterated over */ + JOIN_TAB *join_tab; + /* The join cache used to join the table join_tab */ + JOIN_CACHE *cache; + /* + Representation of the executed multi-way join through which + all needed context can be accessed. + */ + JOIN *join; + +public: + + JOIN_TAB_SCAN(JOIN *j, JOIN_TAB *tab) + { + join= j; + join_tab= tab; + cache= join_tab->cache; + } + + virtual ~JOIN_TAB_SCAN() = default; + + /* + Shall calculate the increment of the auxiliary buffer for a record + write if such a buffer is used by the table scan object + */ + virtual uint aux_buffer_incr(size_t recno) { return 0; } + + /* Initiate the process of iteration over the joined table */ + virtual int open(); + /* + Shall read the next candidate for matches with records from + the join buffer. + */ + virtual int next(); + /* + Perform the finalizing actions for the process of iteration + over the joined_table. + */ + virtual void close(); + +}; + +/* + The class JOIN_CACHE_BNL is used when the BNL join algorithm is + employed to perform a join operation +*/ + +class JOIN_CACHE_BNL :public JOIN_CACHE +{ +private: + /* + The number of the records in the join buffer that have to be + checked yet for a match with the current record of join_tab + read into the record buffer. + */ + uint rem_records; + +protected: + + bool prepare_look_for_matches(bool skip_last); + + uchar *get_next_candidate_for_match(); + + bool skip_next_candidate_for_match(uchar *rec_ptr); + + void read_next_candidate_for_match(uchar *rec_ptr); + +public: + + /* + This constructor creates an unlinked BNL join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + */ + JOIN_CACHE_BNL(JOIN *j, JOIN_TAB *tab) :JOIN_CACHE(j, tab) {} + + /* + This constructor creates a linked BNL join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + */ + JOIN_CACHE_BNL(JOIN *j, JOIN_TAB *tab, JOIN_CACHE *prev) + :JOIN_CACHE(j, tab, prev) {} + + /* Initialize the BNL cache */ + int init(bool for_explain); + + enum Join_algorithm get_join_alg() { return BNL_JOIN_ALG; } + + bool is_key_access() { return FALSE; } + +}; + + +/* + The class JOIN_CACHE_BNLH is used when the BNLH join algorithm is + employed to perform a join operation +*/ + +class JOIN_CACHE_BNLH :public JOIN_CACHE_HASHED +{ + +protected: + + /* + The pointer to the last record from the circular list of the records + that match the join key built out of the record in the join buffer for + the join_tab table + */ + uchar *last_matching_rec_ref_ptr; + /* + The pointer to the next current record from the circular list of the + records that match the join key built out of the record in the join buffer + for the join_tab table. This pointer is used by the class method + get_next_candidate_for_match to iterate over records from the circular + list. + */ + uchar *next_matching_rec_ref_ptr; + + /* + Get the chain of records from buffer matching the current candidate + record for join + */ + uchar *get_matching_chain_by_join_key(); + + bool prepare_look_for_matches(bool skip_last); + + uchar *get_next_candidate_for_match(); + + bool skip_next_candidate_for_match(uchar *rec_ptr); + + void read_next_candidate_for_match(uchar *rec_ptr); + +public: + + /* + This constructor creates an unlinked BNLH join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + */ + JOIN_CACHE_BNLH(JOIN *j, JOIN_TAB *tab) : JOIN_CACHE_HASHED(j, tab) {} + + /* + This constructor creates a linked BNLH join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + */ + JOIN_CACHE_BNLH(JOIN *j, JOIN_TAB *tab, JOIN_CACHE *prev) + : JOIN_CACHE_HASHED(j, tab, prev) {} + + /* Initialize the BNLH cache */ + int init(bool for_explain); + + enum Join_algorithm get_join_alg() { return BNLH_JOIN_ALG; } + + bool is_key_access() { return TRUE; } + +}; + + +/* + The class JOIN_TAB_SCAN_MRR is a companion class for the classes + JOIN_CACHE_BKA and JOIN_CACHE_BKAH. Actually the class implements the + iterator over the records from join_tab selected by BKA/BKAH join + algorithm as the candidates to be joined. + The virtual functions open, next and close are called for any iteration over + join_tab record candidates. The function open is called to initiate the + process of the iteration. The function next shall read the next record from + the set of the record candidates. The record is read into the record buffer + of the joined table. The function close shall perform the finalizing actions + for the iteration. +*/ + +class JOIN_TAB_SCAN_MRR: public JOIN_TAB_SCAN +{ + /* Interface object to generate key ranges for MRR */ + RANGE_SEQ_IF range_seq_funcs; + + /* Number of ranges to be processed by the MRR interface */ + uint ranges; + + /* Flag to to be passed to the MRR interface */ + uint mrr_mode; + + /* MRR buffer assotiated with this join cache */ + HANDLER_BUFFER mrr_buff; + + /* Shall initialize the MRR buffer */ + virtual void init_mrr_buff() + { + cache->setup_aux_buffer(mrr_buff); + } + +public: + + JOIN_TAB_SCAN_MRR(JOIN *j, JOIN_TAB *tab, uint flags, RANGE_SEQ_IF rs_funcs) + :JOIN_TAB_SCAN(j, tab), range_seq_funcs(rs_funcs), mrr_mode(flags) {} + + uint aux_buffer_incr(size_t recno); + + int open(); + + int next(); + + friend class JOIN_CACHE_BKA; /* it needs to add an mrr_mode flag after JOIN_CACHE::init() call */ +}; + +/* + The class JOIN_CACHE_BKA is used when the BKA join algorithm is + employed to perform a join operation +*/ + +class JOIN_CACHE_BKA :public JOIN_CACHE +{ +private: + + /* Flag to to be passed to the companion JOIN_TAB_SCAN_MRR object */ + uint mrr_mode; + + /* + This value is set to 1 by the class prepare_look_for_matches method + and back to 0 by the class get_next_candidate_for_match method + */ + uint rem_records; + + /* + This field contains the current association label set by a call of + the multi_range_read_next handler function. + See the function JOIN_CACHE_BKA::get_curr_key_association() + */ + uchar *curr_association; + +protected: + + /* + Get the number of ranges in the cache buffer passed to the MRR + interface. For each record its own range is passed. + */ + uint get_number_of_ranges_for_mrr() { return (uint)records; } + + /* + Setup the MRR buffer as the space between the last record put + into the join buffer and the very end of the join buffer + */ + int setup_aux_buffer(HANDLER_BUFFER &aux_buff) + { + aux_buff.buffer= end_pos; + aux_buff.buffer_end= buff+buff_size; + return 0; + } + + bool prepare_look_for_matches(bool skip_last); + + uchar *get_next_candidate_for_match(); + + bool skip_next_candidate_for_match(uchar *rec_ptr); + + void read_next_candidate_for_match(uchar *rec_ptr); + +public: + + /* + This constructor creates an unlinked BKA join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + The MRR mode initially is set to 'flags'. + */ + JOIN_CACHE_BKA(JOIN *j, JOIN_TAB *tab, uint flags) + :JOIN_CACHE(j, tab), mrr_mode(flags) {} + /* + This constructor creates a linked BKA join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + The MRR mode initially is set to 'flags'. + */ + JOIN_CACHE_BKA(JOIN *j, JOIN_TAB *tab, uint flags, JOIN_CACHE *prev) + :JOIN_CACHE(j, tab, prev), mrr_mode(flags) {} + + JOIN_CACHE_BKA(JOIN_CACHE_BKA *bka) + :JOIN_CACHE(bka->join, bka->join_tab, bka->prev_cache), + mrr_mode(bka->mrr_mode) {} + + uchar **get_curr_association_ptr() { return &curr_association; } + + /* Initialize the BKA cache */ + int init(bool for_explain); + + enum Join_algorithm get_join_alg() { return BKA_JOIN_ALG; } + + bool is_key_access() { return TRUE; } + + /* Get the key built over the next record from the join buffer */ + uint get_next_key(uchar **key); + + /* Check index condition of the joined table for a record from BKA cache */ + bool skip_index_tuple(range_id_t range_info); + + bool save_explain_data(EXPLAIN_BKA_TYPE *explain); +}; + + + +/* + The class JOIN_CACHE_BKAH is used when the BKAH join algorithm is + employed to perform a join operation +*/ + +class JOIN_CACHE_BKAH :public JOIN_CACHE_BNLH +{ + +private: + /* Flag to to be passed to the companion JOIN_TAB_SCAN_MRR object */ + uint mrr_mode; + + /* + This flag is set to TRUE if the implementation of the MRR interface cannot + handle range association labels and does not return them to the caller of + the multi_range_read_next handler function. E.g. the implementation of + the MRR inteface for the Falcon engine could not return association + labels to the caller of multi_range_read_next. + The flag is set by JOIN_CACHE_BKA::init() and is not ever changed. + */ + bool no_association; + + /* + This field contains the association label returned by the + multi_range_read_next function. + See the function JOIN_CACHE_BKAH::get_curr_key_association() + */ + uchar *curr_matching_chain; + +protected: + + uint get_number_of_ranges_for_mrr() { return key_entries; } + + /* + Initialize the MRR buffer allocating some space within the join buffer. + The entire space between the last record put into the join buffer and the + last key entry added to the hash table is used for the MRR buffer. + */ + int setup_aux_buffer(HANDLER_BUFFER &aux_buff) + { + aux_buff.buffer= end_pos; + aux_buff.buffer_end= last_key_entry; + return 0; + } + + bool prepare_look_for_matches(bool skip_last); + + /* + The implementations of the methods + - get_next_candidate_for_match + - skip_recurrent_candidate_for_match + - read_next_candidate_for_match + are inherited from the JOIN_CACHE_BNLH class + */ + +public: + + /* + This constructor creates an unlinked BKAH join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. + The MRR mode initially is set to 'flags'. + */ + JOIN_CACHE_BKAH(JOIN *j, JOIN_TAB *tab, uint flags) + :JOIN_CACHE_BNLH(j, tab), mrr_mode(flags) {} + + /* + This constructor creates a linked BKAH join cache. The cache is to be + used to join table 'tab' to the result of joining the previous tables + specified by the 'j' parameter. The parameter 'prev' specifies the previous + cache object to which this cache is linked. + The MRR mode initially is set to 'flags'. + */ + JOIN_CACHE_BKAH(JOIN *j, JOIN_TAB *tab, uint flags, JOIN_CACHE *prev) + :JOIN_CACHE_BNLH(j, tab, prev), mrr_mode(flags) {} + + JOIN_CACHE_BKAH(JOIN_CACHE_BKAH *bkah) + :JOIN_CACHE_BNLH(bkah->join, bkah->join_tab, bkah->prev_cache), + mrr_mode(bkah->mrr_mode) {} + + uchar **get_curr_association_ptr() { return &curr_matching_chain; } + + /* Initialize the BKAH cache */ + int init(bool for_explain); + + enum Join_algorithm get_join_alg() { return BKAH_JOIN_ALG; } + + /* Check index condition of the joined table for a record from BKAH cache */ + bool skip_index_tuple(range_id_t range_info); + + bool save_explain_data(EXPLAIN_BKA_TYPE *explain); +}; |