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EDIT :: opt_rewrite_date_cmp.h

/* Copyright (c) 2023, 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 Street, Fifth Floor, Boston, MA 02110-1335 USA */ #ifndef OPT_REWRITE_DATE_CMP_INCLUDED #define OPT_REWRITE_DATE_CMP_INCLUDED class Item_func_eq; class Item_func_ge; class Item_func_gt; class Item_func_le; class Item_func_lt; class Item_bool_rowready_func2; /* @brief Class responsible for rewriting datetime comparison condition. It rewrites non-sargable conditions into sargable. @detail The intent of this class is to do equivalent rewrites as follows: YEAR(col) <= val -> col <= year_end(val) YEAR(col) < val -> col < year_start(val) YEAR(col) >= val -> col >= year_start(val) YEAR(col) > val -> col > year_end(val) YEAR(col) = val -> col >= year_start(val) AND col<=year_end(val) Also the same is done for comparisons with DATE(col): DATE(col) <= val -> col <= day_end(val) if col has a DATE type (not DATETIME), then the rewrite becomes: DATE(col) <= val -> col <= val @usage Date_cmp_func_rewriter rwr(thd, item_func); Item *new_item= rwr.get_rewrite_result(); Returned new_item points to an item that item_func was rewritten to. new_item already has fixed fields (fix_fields() was called). If no rewrite happened, new_item points to the initial item_func parameter @todo Also handle conditions in form "YEAR(date_col) BETWEEN 2014 AND 2017" and "YEAR(col) = c1 AND MONTH(col) = c2" */ class Date_cmp_func_rewriter { public: Date_cmp_func_rewriter(THD* thd, Item_func_eq *item_func); Date_cmp_func_rewriter(THD* thd, Item_func_ge *item_func); Date_cmp_func_rewriter(THD* thd, Item_func_gt *item_func); Date_cmp_func_rewriter(THD* thd, Item_func_le *item_func); Date_cmp_func_rewriter(THD* thd, Item_func_lt *item_func); Item* get_rewrite_result() const { return result; } Date_cmp_func_rewriter() = delete; Date_cmp_func_rewriter(const Date_cmp_func_rewriter&) = delete; Date_cmp_func_rewriter(Date_cmp_func_rewriter&&) = delete; private: bool check_cond_match_and_prepare(Item_bool_rowready_func2 *item_func); Item_field *is_date_rounded_field(Item* item, const Type_handler *comparison_type, Item_func::Functype *out_func_type) const; void rewrite_le_gt_lt_ge(); Item *create_bound(uint month, uint day, const TimeOfDay6 &td) const; Item *create_start_bound() const { return create_bound(1, 1, TimeOfDay6()); } Item *create_end_bound() const { return create_bound(12, 31, TimeOfDay6::end_of_day(field_ref->decimals)); } Item *create_cmp_func(Item_func::Functype func_type, Item *arg1, Item *arg2); THD *thd= nullptr; Item *const_arg_value= nullptr; Item_func::Functype rewrite_func_type= Item_func::UNKNOWN_FUNC; Item_func::Functype argument_func_type= Item_func::UNKNOWN_FUNC; Item_field *field_ref= nullptr; Item *result= nullptr; }; void trace_date_item_rewrite(THD *thd,Item *new_item, Item *old_item); template<typename T> Item* do_date_conds_transformation(THD *thd, T *item) { Date_cmp_func_rewriter rwr(thd, item); /* If the rewrite failed for some reason, we get the original item */ Item *new_item= rwr.get_rewrite_result(); trace_date_item_rewrite(thd, new_item, item); return new_item; } #endif

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