diff options
Diffstat (limited to '')
| -rw-r--r-- | sql/item_windowfunc.h | 1398 |
1 files changed, 1398 insertions, 0 deletions
diff --git a/sql/item_windowfunc.h b/sql/item_windowfunc.h new file mode 100644 index 00000000..0dfc683c --- /dev/null +++ b/sql/item_windowfunc.h @@ -0,0 +1,1398 @@ +/* + Copyright (c) 2016, 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 02110-1301 USA */ + +#ifndef ITEM_WINDOWFUNC_INCLUDED +#define ITEM_WINDOWFUNC_INCLUDED + +#include "item.h" + +class Window_spec; + + +int test_if_group_changed(List<Cached_item> &list); + + +/* A wrapper around test_if_group_changed */ +class Group_bound_tracker +{ +public: + + Group_bound_tracker(THD *thd, SQL_I_List<ORDER> *list) + { + for (ORDER *curr = list->first; curr; curr=curr->next) + { + Cached_item *tmp= new_Cached_item(thd, curr->item[0], TRUE); + group_fields.push_back(tmp); + } + } + + void init() + { + first_check= true; + } + + /* + Check if the current row is in a different group than the previous row + this function was called for. + XXX: Side-effect: The new row's group becomes the current row's group. + + Returns true if there is a change between the current_group and the cached + value, or if it is the first check after a call to init. + */ + bool check_if_next_group() + { + if (test_if_group_changed(group_fields) > -1 || first_check) + { + first_check= false; + return true; + } + return false; + } + + /* + Check if the current row is in a different group than the previous row + check_if_next_group was called for. + + Compares the groups without the additional side effect of updating the + current cached values. + */ + int compare_with_cache() + { + List_iterator<Cached_item> li(group_fields); + Cached_item *ptr; + int res; + while ((ptr= li++)) + { + if ((res= ptr->cmp_read_only())) + return res; + } + return 0; + } + ~Group_bound_tracker() + { + group_fields.delete_elements(); + } + +private: + List<Cached_item> group_fields; + /* + During the first check_if_next_group, the list of cached_items is not + initialized. The compare function will return that the items match if + the field's value is the same as the Cached_item's default value (0). + This flag makes sure that we always return true during the first check. + + XXX This is better to be implemented within test_if_group_changed, but + since it is used in other parts of the codebase, we keep it here for now. + */ + bool first_check; +}; + +/* + ROW_NUMBER() OVER (...) + + @detail + - This is a Window function (not just an aggregate) + - It can be computed by doing one pass over select output, provided + the output is sorted according to the window definition. +*/ + +class Item_sum_row_number: public Item_sum_int +{ + longlong count; + +public: + + Item_sum_row_number(THD *thd) + : Item_sum_int(thd), count(0) {} + + const Type_handler *type_handler() const override + { return &type_handler_slonglong; } + + void clear() override + { + count= 0; + } + + bool add() override + { + count++; + return false; + } + + void reset_field() override { DBUG_ASSERT(0); } + void update_field() override {} + + enum Sumfunctype sum_func() const override + { + return ROW_NUMBER_FUNC; + } + + longlong val_int() override + { + return count; + } + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("row_number") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_row_number>(thd, this); } +}; + + +/* + RANK() OVER (...) Windowing function + + @detail + - This is a Window function (not just an aggregate) + - It can be computed by doing one pass over select output, provided + the output is sorted according to the window definition. + + The function is defined as: + + "The rank of row R is defined as 1 (one) plus the number of rows that + precede R and are not peers of R" + + "This implies that if two or more rows are not distinct with respect to + the window ordering, then there will be one or more" +*/ + +class Item_sum_rank: public Item_sum_int +{ +protected: + longlong row_number; // just ROW_NUMBER() + longlong cur_rank; // current value + + Group_bound_tracker *peer_tracker; +public: + + Item_sum_rank(THD *thd) : Item_sum_int(thd), peer_tracker(NULL) {} + + const Type_handler *type_handler() const override + { return &type_handler_slonglong; } + + void clear() override + { + /* This is called on partition start */ + cur_rank= 1; + row_number= 0; + } + + bool add() override; + + longlong val_int() override + { + return cur_rank; + } + + void reset_field() override { DBUG_ASSERT(0); } + void update_field() override {} + + enum Sumfunctype sum_func () const override + { + return RANK_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("rank") }; + return name; + } + + void setup_window_func(THD *thd, Window_spec *window_spec) override; + + void cleanup() override + { + if (peer_tracker) + { + delete peer_tracker; + peer_tracker= NULL; + } + Item_sum_int::cleanup(); + } + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_rank>(thd, this); } +}; + + +/* + DENSE_RANK() OVER (...) Windowing function + + @detail + - This is a Window function (not just an aggregate) + - It can be computed by doing one pass over select output, provided + the output is sorted according to the window definition. + + The function is defined as: + + "If DENSE_RANK is specified, then the rank of row R is defined as the + number of rows preceding and including R that are distinct with respect + to the window ordering" + + "This implies that there are no gaps in the sequential rank numbering of + rows in each window partition." +*/ + + +class Item_sum_dense_rank: public Item_sum_int +{ + longlong dense_rank; + bool first_add; + Group_bound_tracker *peer_tracker; + public: + /* + XXX(cvicentiu) This class could potentially be implemented in the rank + class, with a switch for the DENSE case. + */ + void clear() override + { + dense_rank= 0; + first_add= true; + } + bool add() override; + void reset_field() override { DBUG_ASSERT(0); } + void update_field() override {} + longlong val_int() override + { + return dense_rank; + } + + Item_sum_dense_rank(THD *thd) + : Item_sum_int(thd), dense_rank(0), first_add(true), peer_tracker(NULL) {} + const Type_handler *type_handler() const override + { return &type_handler_slonglong; } + enum Sumfunctype sum_func () const override + { + return DENSE_RANK_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("dense_rank") }; + return name; + } + + void setup_window_func(THD *thd, Window_spec *window_spec) override; + + void cleanup() override + { + if (peer_tracker) + { + delete peer_tracker; + peer_tracker= NULL; + } + Item_sum_int::cleanup(); + } + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_dense_rank>(thd, this); } +}; + +class Item_sum_hybrid_simple : public Item_sum_hybrid +{ + public: + Item_sum_hybrid_simple(THD *thd, Item *arg): + Item_sum_hybrid(thd, arg), + value(NULL) + { } + + Item_sum_hybrid_simple(THD *thd, Item *arg1, Item *arg2): + Item_sum_hybrid(thd, arg1, arg2), + value(NULL) + { } + + bool add() override; + bool fix_fields(THD *, Item **) override; + bool fix_length_and_dec(THD *thd) override; + void setup_hybrid(THD *thd, Item *item); + double val_real() override; + longlong val_int() override; + my_decimal *val_decimal(my_decimal *) override; + void reset_field() override; + String *val_str(String *) override; + bool val_native(THD *thd, Native *to) override; + bool get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate) override; + const Type_handler *type_handler() const override + { return Type_handler_hybrid_field_type::type_handler(); } + void update_field() override; + Field *create_tmp_field(MEM_ROOT *root, bool group, TABLE *table) override; + void clear() override + { + value->clear(); + null_value= 1; + } + + private: + Item_cache *value; +}; + +/* + This item will remember the first value added to it. It will not update + the value unless it is cleared. +*/ +class Item_sum_first_value : public Item_sum_hybrid_simple +{ + public: + Item_sum_first_value(THD* thd, Item* arg_expr) : + Item_sum_hybrid_simple(thd, arg_expr) {} + + + enum Sumfunctype sum_func () const override + { + return FIRST_VALUE_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("first_value") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_first_value>(thd, this); } +}; + +/* + This item will remember the last value added to it. + + This item does not support removal, and can be cleared only by calling + clear(). +*/ +class Item_sum_last_value : public Item_sum_hybrid_simple +{ + public: + Item_sum_last_value(THD* thd, Item* arg_expr) : + Item_sum_hybrid_simple(thd, arg_expr) {} + + enum Sumfunctype sum_func() const override + { + return LAST_VALUE_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("last_value") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_last_value>(thd, this); } +}; + + +class Item_sum_nth_value : public Item_sum_hybrid_simple +{ + public: + Item_sum_nth_value(THD *thd, Item *arg_expr, Item* offset_expr) : + Item_sum_hybrid_simple(thd, arg_expr, offset_expr) {} + + enum Sumfunctype sum_func() const override + { + return NTH_VALUE_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("nth_value") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_nth_value>(thd, this); } +}; + + +class Item_sum_lead : public Item_sum_hybrid_simple +{ + public: + Item_sum_lead(THD *thd, Item *arg_expr, Item* offset_expr) : + Item_sum_hybrid_simple(thd, arg_expr, offset_expr) {} + + enum Sumfunctype sum_func() const override + { + return LEAD_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("lead") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_lead>(thd, this); } +}; + + +class Item_sum_lag : public Item_sum_hybrid_simple +{ + public: + Item_sum_lag(THD *thd, Item *arg_expr, Item* offset_expr) : + Item_sum_hybrid_simple(thd, arg_expr, offset_expr) {} + + enum Sumfunctype sum_func() const override + { + return LAG_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("lag") }; + return name; + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_lag>(thd, this); } +}; + + +class Partition_row_count +{ +public: + Partition_row_count() :partition_row_count_(0) { } + void set_partition_row_count(ulonglong count) + { + partition_row_count_ = count; + } + double calc_val_real(bool *null_value, + ulonglong current_row_count) + { + if ((*null_value= (partition_row_count_ == 0))) + return 0; + return static_cast<double>(current_row_count) / partition_row_count_; + } +protected: + longlong get_row_count() { return partition_row_count_; } + ulonglong partition_row_count_; +}; + + +class Current_row_count +{ +public: + Current_row_count() :current_row_count_(0) { } +protected: + ulonglong get_row_number() { return current_row_count_ ; } + ulonglong current_row_count_; +}; + + +/* + @detail + "The relative rank of a row R is defined as (RK-1)/(NR-1), where RK is + defined to be the RANK of R and NR is defined to be the number of rows in + the window partition of R." + + Computation of this function requires two passes: + - First pass to find #rows in the partition + This is held within the row_count context. + - Second pass to compute rank of current row and the value of the function +*/ +class Item_sum_percent_rank: public Item_sum_double, + public Partition_row_count +{ + public: + Item_sum_percent_rank(THD *thd) + : Item_sum_double(thd), cur_rank(1), peer_tracker(NULL) {} + + longlong val_int() override + { + /* + Percent rank is a real value so calling the integer value should never + happen. It makes no sense as it gets truncated to either 0 or 1. + */ + DBUG_ASSERT(0); + return 0; + } + + double val_real() override + { + /* + We can not get the real value without knowing the number of rows + in the partition. Don't divide by 0. + */ + ulonglong partition_rows = get_row_count(); + null_value= partition_rows > 0 ? false : true; + + return partition_rows > 1 ? + static_cast<double>(cur_rank - 1) / (partition_rows - 1) : 0; + } + + enum Sumfunctype sum_func () const override + { + return PERCENT_RANK_FUNC; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("percent_rank") }; + return name; + } + + void update_field() override {} + + void clear() override + { + cur_rank= 1; + row_number= 0; + } + bool add() override; + const Type_handler *type_handler() const override + { return &type_handler_double; } + + bool fix_length_and_dec(THD *thd) override + { + decimals = 10; // TODO-cvicentiu find out how many decimals the standard + // requires. + return FALSE; + } + + void setup_window_func(THD *thd, Window_spec *window_spec) override; + + void reset_field() override { DBUG_ASSERT(0); } + + void set_partition_row_count(ulonglong count) override + { + Partition_row_count::set_partition_row_count(count); + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_percent_rank>(thd, this); } + + private: + longlong cur_rank; // Current rank of the current row. + longlong row_number; // Value if this were ROW_NUMBER() function. + + Group_bound_tracker *peer_tracker; + + void cleanup() override + { + if (peer_tracker) + { + delete peer_tracker; + peer_tracker= NULL; + } + Item_sum_num::cleanup(); + } +}; + + + + +/* + @detail + "The relative rank of a row R is defined as NP/NR, where + - NP is defined to be the number of rows preceding or peer with R in the + window ordering of the window partition of R + - NR is defined to be the number of rows in the window partition of R. + + Just like with Item_sum_percent_rank, computation of this function requires + two passes. +*/ + +class Item_sum_cume_dist: public Item_sum_double, + public Partition_row_count, + public Current_row_count +{ + public: + Item_sum_cume_dist(THD *thd) :Item_sum_double(thd) { } + Item_sum_cume_dist(THD *thd, Item *arg) :Item_sum_double(thd, arg) { } + + double val_real() override + { + return calc_val_real(&null_value, current_row_count_); + } + + bool add() override + { + current_row_count_++; + return false; + } + + enum Sumfunctype sum_func() const override + { + return CUME_DIST_FUNC; + } + + void clear() override + { + current_row_count_= 0; + partition_row_count_= 0; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("cume_dist") }; + return name; + } + + void update_field() override {} + const Type_handler *type_handler() const override + { return &type_handler_double; } + + bool fix_length_and_dec(THD *thd) override + { + decimals = 10; // TODO-cvicentiu find out how many decimals the standard + // requires. + return FALSE; + } + + void reset_field() override { DBUG_ASSERT(0); } + + void set_partition_row_count(ulonglong count) override + { + Partition_row_count::set_partition_row_count(count); + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_cume_dist>(thd, this); } + +}; + +class Item_sum_ntile : public Item_sum_int, + public Partition_row_count, + public Current_row_count +{ + public: + Item_sum_ntile(THD* thd, Item* num_quantiles_expr) : + Item_sum_int(thd, num_quantiles_expr), n_old_val_(0) + { } + + longlong val_int() override + { + if (get_row_count() == 0) + { + null_value= true; + return 0; + } + + longlong num_quantiles= get_num_quantiles(); + + if (num_quantiles <= 0 || + (static_cast<ulonglong>(num_quantiles) != n_old_val_ && n_old_val_ > 0)) + { + my_error(ER_INVALID_NTILE_ARGUMENT, MYF(0)); + return true; + } + n_old_val_= static_cast<ulonglong>(num_quantiles); + null_value= false; + ulonglong quantile_size = get_row_count() / num_quantiles; + ulonglong extra_rows = get_row_count() - quantile_size * num_quantiles; + + if (current_row_count_ <= extra_rows * (quantile_size + 1)) + return (current_row_count_ - 1) / (quantile_size + 1) + 1; + + return (current_row_count_ - 1 - extra_rows) / quantile_size + 1; + } + + bool add() override + { + current_row_count_++; + return false; + } + + enum Sumfunctype sum_func() const override + { + return NTILE_FUNC; + } + + void clear() override + { + current_row_count_= 0; + partition_row_count_= 0; + n_old_val_= 0; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("ntile") }; + return name; + } + + void update_field() override {} + + const Type_handler *type_handler() const override + { return &type_handler_slonglong; } + + void reset_field() override { DBUG_ASSERT(0); } + + void set_partition_row_count(ulonglong count) override + { + Partition_row_count::set_partition_row_count(count); + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_ntile>(thd, this); } + + private: + longlong get_num_quantiles() { return args[0]->val_int(); } + ulonglong n_old_val_; +}; + +class Item_sum_percentile_disc : public Item_sum_num, + public Type_handler_hybrid_field_type, + public Partition_row_count, + public Current_row_count +{ +public: + Item_sum_percentile_disc(THD *thd, Item* arg) : Item_sum_num(thd, arg), + Type_handler_hybrid_field_type(&type_handler_slonglong), + value(NULL), val_calculated(FALSE), first_call(TRUE), + prev_value(0), order_item(NULL){} + + double val_real() override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return 0; + } + null_value= false; + return value->val_real(); + } + + longlong val_int() override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return 0; + } + null_value= false; + return value->val_int(); + } + + my_decimal* val_decimal(my_decimal* dec) override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return 0; + } + null_value= false; + return value->val_decimal(dec); + } + + String* val_str(String *str) override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return 0; + } + null_value= false; + return value->val_str(str); + } + + bool get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate) override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return true; + } + null_value= false; + return value->get_date(thd, ltime, fuzzydate); + } + + bool val_native(THD *thd, Native *to) override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return true; + } + null_value= false; + return value->val_native(thd, to); + } + + bool add() override + { + Item *arg= get_arg(0); + if (arg->is_null()) + return false; + + if (first_call) + { + prev_value= arg->val_real(); + if (prev_value > 1 || prev_value < 0) + { + my_error(ER_ARGUMENT_OUT_OF_RANGE, MYF(0), func_name()); + return true; + } + first_call= false; + } + + double arg_val= arg->val_real(); + + if (prev_value != arg_val) + { + my_error(ER_ARGUMENT_NOT_CONSTANT, MYF(0), func_name()); + return true; + } + + if (val_calculated) + return false; + + value->store(order_item); + value->cache_value(); + if (value->null_value) + return false; + + current_row_count_++; + double val= calc_val_real(&null_value, current_row_count_); + + if (val >= prev_value && !val_calculated) + val_calculated= true; + return false; + } + + enum Sumfunctype sum_func() const override + { + return PERCENTILE_DISC_FUNC; + } + + void clear() override + { + val_calculated= false; + first_call= true; + value->clear(); + partition_row_count_= 0; + current_row_count_= 0; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("percentile_disc") }; + return name; + } + + void update_field() override {} + const Type_handler *type_handler() const override + {return Type_handler_hybrid_field_type::type_handler();} + + bool fix_length_and_dec(THD *thd) override + { + decimals = 10; // TODO-cvicentiu find out how many decimals the standard + // requires. + return FALSE; + } + + void reset_field() override { DBUG_ASSERT(0); } + + void set_partition_row_count(ulonglong count) override + { + Partition_row_count::set_partition_row_count(count); + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_percentile_disc>(thd, this); } + void setup_window_func(THD *thd, Window_spec *window_spec) override; + void setup_hybrid(THD *thd, Item *item); + bool fix_fields(THD *thd, Item **ref) override; + +private: + Item_cache *value; + bool val_calculated; + bool first_call; + double prev_value; + Item *order_item; +}; + +class Item_sum_percentile_cont : public Item_sum_double, + public Partition_row_count, + public Current_row_count +{ +public: + Item_sum_percentile_cont(THD *thd, Item* arg) : Item_sum_double(thd, arg), + floor_value(NULL), ceil_value(NULL), first_call(TRUE),prev_value(0), + ceil_val_calculated(FALSE), floor_val_calculated(FALSE), order_item(NULL){} + + double val_real() override + { + if (get_row_count() == 0 || get_arg(0)->is_null()) + { + null_value= true; + return 0; + } + null_value= false; + double val= 1 + prev_value * (get_row_count()-1); + + /* + Applying the formula to get the value + If (CRN = FRN = RN) then the result is (value of expression from row at RN) + Otherwise the result is + (CRN - RN) * (value of expression for row at FRN) + + (RN - FRN) * (value of expression for row at CRN) + */ + + if(ceil(val) == floor(val)) + return floor_value->val_real(); + + double ret_val= ((val - floor(val)) * ceil_value->val_real()) + + ((ceil(val) - val) * floor_value->val_real()); + + return ret_val; + } + + bool add() override + { + Item *arg= get_arg(0); + if (arg->is_null()) + return false; + + if (first_call) + { + first_call= false; + prev_value= arg->val_real(); + if (prev_value > 1 || prev_value < 0) + { + my_error(ER_ARGUMENT_OUT_OF_RANGE, MYF(0), func_name()); + return true; + } + } + + double arg_val= arg->val_real(); + if (prev_value != arg_val) + { + my_error(ER_ARGUMENT_NOT_CONSTANT, MYF(0), func_name()); + return true; + } + + if (!floor_val_calculated) + { + floor_value->store(order_item); + floor_value->cache_value(); + if (floor_value->null_value) + return false; + } + if (floor_val_calculated && !ceil_val_calculated) + { + ceil_value->store(order_item); + ceil_value->cache_value(); + if (ceil_value->null_value) + return false; + } + + current_row_count_++; + double val= 1 + prev_value * (get_row_count()-1); + + if (!floor_val_calculated && get_row_number() == floor(val)) + floor_val_calculated= true; + + if (!ceil_val_calculated && get_row_number() == ceil(val)) + ceil_val_calculated= true; + return false; + } + + enum Sumfunctype sum_func() const override + { + return PERCENTILE_CONT_FUNC; + } + + void clear() override + { + first_call= true; + floor_value->clear(); + ceil_value->clear(); + floor_val_calculated= false; + ceil_val_calculated= false; + partition_row_count_= 0; + current_row_count_= 0; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("percentile_cont") }; + return name; + } + void update_field() override {} + + bool fix_length_and_dec(THD *thd) override + { + decimals = 10; // TODO-cvicentiu find out how many decimals the standard + // requires. + return FALSE; + } + + void reset_field() override { DBUG_ASSERT(0); } + + void set_partition_row_count(ulonglong count) override + { + Partition_row_count::set_partition_row_count(count); + } + + Item *get_copy(THD *thd) override + { return get_item_copy<Item_sum_percentile_cont>(thd, this); } + void setup_window_func(THD *thd, Window_spec *window_spec) override; + void setup_hybrid(THD *thd, Item *item); + bool fix_fields(THD *thd, Item **ref) override; + +private: + Item_cache *floor_value; + Item_cache *ceil_value; + bool first_call; + double prev_value; + bool ceil_val_calculated; + bool floor_val_calculated; + Item *order_item; +}; + + + + +class Item_window_func : public Item_func_or_sum +{ + /* Window function parameters as we've got them from the parser */ +public: + LEX_CSTRING *window_name; +public: + Window_spec *window_spec; + +public: + Item_window_func(THD *thd, Item_sum *win_func, LEX_CSTRING *win_name) + : Item_func_or_sum(thd, (Item *) win_func), + window_name(win_name), window_spec(NULL), + force_return_blank(true), + read_value_from_result_field(false) {} + + Item_window_func(THD *thd, Item_sum *win_func, Window_spec *win_spec) + : Item_func_or_sum(thd, (Item *) win_func), + window_name(NULL), window_spec(win_spec), + force_return_blank(true), + read_value_from_result_field(false) {} + + Item_sum *window_func() const { return (Item_sum *) args[0]; } + + void update_used_tables() override; + + /* + This is used by filesort to mark the columns it needs to read (because they + participate in the sort criteria and/or row retrieval. Window functions can + only be used in sort criteria). + + Sorting by window function value is only done after the window functions + have been computed. In that case, window function will need to read its + temp.table field. In order to allow that, mark that field in the read_set. + */ + bool register_field_in_read_map(void *arg) override + { + TABLE *table= (TABLE*) arg; + if (result_field && (result_field->table == table || !table)) + { + bitmap_set_bit(result_field->table->read_set, result_field->field_index); + } + return 0; + } + + bool is_frame_prohibited() const + { + switch (window_func()->sum_func()) { + case Item_sum::ROW_NUMBER_FUNC: + case Item_sum::RANK_FUNC: + case Item_sum::DENSE_RANK_FUNC: + case Item_sum::PERCENT_RANK_FUNC: + case Item_sum::CUME_DIST_FUNC: + case Item_sum::NTILE_FUNC: + case Item_sum::PERCENTILE_CONT_FUNC: + case Item_sum::PERCENTILE_DISC_FUNC: + return true; + default: + return false; + } + } + + bool requires_special_cursors() const + { + switch (window_func()->sum_func()) { + case Item_sum::FIRST_VALUE_FUNC: + case Item_sum::LAST_VALUE_FUNC: + case Item_sum::NTH_VALUE_FUNC: + case Item_sum::LAG_FUNC: + case Item_sum::LEAD_FUNC: + return true; + default: + return false; + } + } + + bool requires_partition_size() const + { + switch (window_func()->sum_func()) { + case Item_sum::PERCENT_RANK_FUNC: + case Item_sum::CUME_DIST_FUNC: + case Item_sum::NTILE_FUNC: + case Item_sum::PERCENTILE_CONT_FUNC: + case Item_sum::PERCENTILE_DISC_FUNC: + return true; + default: + return false; + } + } + + bool requires_peer_size() const + { + switch (window_func()->sum_func()) { + case Item_sum::CUME_DIST_FUNC: + return true; + default: + return false; + } + } + + bool is_order_list_mandatory() const + { + switch (window_func()->sum_func()) { + case Item_sum::RANK_FUNC: + case Item_sum::DENSE_RANK_FUNC: + case Item_sum::PERCENT_RANK_FUNC: + case Item_sum::CUME_DIST_FUNC: + case Item_sum::LAG_FUNC: + case Item_sum::LEAD_FUNC: + case Item_sum::PERCENTILE_CONT_FUNC: + case Item_sum::PERCENTILE_DISC_FUNC: + return true; + default: + return false; + } + } + + bool only_single_element_order_list() const + { + switch (window_func()->sum_func()){ + case Item_sum::PERCENTILE_CONT_FUNC: + case Item_sum::PERCENTILE_DISC_FUNC: + return true; + default: + return false; + } + } + + bool check_result_type_of_order_item(); + + + + /* + Computation functions. + TODO: consoder merging these with class Group_bound_tracker. + */ + void setup_partition_border_check(THD *thd); + + const Type_handler *type_handler() const override + { + return ((Item_sum *) args[0])->type_handler(); + } + enum Item::Type type() const override { return Item::WINDOW_FUNC_ITEM; } + +private: + /* + Window functions are very special functions, so val_() methods have + special meaning for them: + + - Phase#1, "Initial" we run the join and put its result into temporary + table. For window functions, we write the default value (NULL?) as + a placeholder. + + - Phase#2: "Computation": executor does the scan in {PARTITION, ORDER BY} + order of this window function. It calls appropriate methods to inform + the window function about rows entering/leaving the window. + It calls window_func()->val_int() so that current window function value + can be saved and stored in the temp.table. + + - Phase#3: "Retrieval" the temporary table is read and passed to query + output. However, Item_window_func still remains in the select list, + so item_windowfunc->val_int() will be called. + During Phase#3, read_value_from_result_field= true. + */ + bool force_return_blank; + bool read_value_from_result_field; + void print_for_percentile_functions(String *str, enum_query_type query_type); + +public: + void set_phase_to_initial() + { + force_return_blank= true; + read_value_from_result_field= false; + } + void set_phase_to_computation() + { + force_return_blank= false; + read_value_from_result_field= false; + } + void set_phase_to_retrieval() + { + force_return_blank= false; + read_value_from_result_field= true; + } + + bool is_null() override + { + if (force_return_blank) + return true; + + if (read_value_from_result_field) + return result_field->is_null(); + + return window_func()->is_null(); + } + + double val_real() override + { + double res; + if (force_return_blank) + { + res= 0.0; + null_value= true; + } + else if (read_value_from_result_field) + { + res= result_field->val_real(); + null_value= result_field->is_null(); + } + else + { + res= window_func()->val_real(); + null_value= window_func()->null_value; + } + return res; + } + + longlong val_int() override + { + longlong res; + if (force_return_blank) + { + res= 0; + null_value= true; + } + else if (read_value_from_result_field) + { + res= result_field->val_int(); + null_value= result_field->is_null(); + } + else + { + res= window_func()->val_int(); + null_value= window_func()->null_value; + } + return res; + } + + String* val_str(String* str) override + { + String *res; + if (force_return_blank) + { + null_value= true; + res= NULL; + } + else if (read_value_from_result_field) + { + if ((null_value= result_field->is_null())) + res= NULL; + else + res= result_field->val_str(str); + } + else + { + res= window_func()->val_str(str); + null_value= window_func()->null_value; + } + return res; + } + + bool val_native(THD *thd, Native *to) override + { + if (force_return_blank) + return null_value= true; + if (read_value_from_result_field) + return val_native_from_field(result_field, to); + return val_native_from_item(thd, window_func(), to); + } + + my_decimal* val_decimal(my_decimal* dec) override + { + my_decimal *res; + if (force_return_blank) + { + null_value= true; + res= NULL; + } + else if (read_value_from_result_field) + { + if ((null_value= result_field->is_null())) + res= NULL; + else + res= result_field->val_decimal(dec); + } + else + { + res= window_func()->val_decimal(dec); + null_value= window_func()->null_value; + } + return res; + } + + bool get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate) override + { + bool res; + if (force_return_blank) + { + null_value= true; + res= true; + } + else if (read_value_from_result_field) + { + if ((null_value= result_field->is_null())) + res= true; + else + res= result_field->get_date(ltime, fuzzydate); + } + else + { + res= window_func()->get_date(thd, ltime, fuzzydate); + null_value= window_func()->null_value; + } + return res; + } + + void split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array, + List<Item> &fields, uint flags) override; + + bool fix_length_and_dec(THD *thd) override + { + Type_std_attributes::set(window_func()); + return FALSE; + } + + LEX_CSTRING func_name_cstring() const override + { + static LEX_CSTRING name= {STRING_WITH_LEN("WF") }; + return name; + } + + bool fix_fields(THD *thd, Item **ref) override; + + bool resolve_window_name(THD *thd); + + void print(String *str, enum_query_type query_type) override; + + Item *get_copy(THD *thd) override { return 0; } + +}; + +#endif /* ITEM_WINDOWFUNC_INCLUDED */ |