diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 92 |
1 files changed, 70 insertions, 22 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index bcd7e8c4a9d..d62032c2b44 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1,9 +1,8 @@ -/* Copyright (C) 2000-2004 MySQL AB & MySQL Finland AB & TCX DataKonsult AB +/* Copyright (C) 2000-2006 MySQL 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; either version 2 of the License, or - (at your option) any later version. + 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 @@ -82,7 +81,7 @@ static store_key *get_store_key(THD *thd, static bool make_simple_join(JOIN *join,TABLE *tmp_table); static void make_outerjoin_info(JOIN *join); static bool make_join_select(JOIN *join,SQL_SELECT *select,COND *item); -static void make_join_readinfo(JOIN *join,uint options); +static void make_join_readinfo(JOIN *join, ulonglong options); static bool only_eq_ref_tables(JOIN *join, ORDER *order, table_map tables); static void update_depend_map(JOIN *join); static void update_depend_map(JOIN *join, ORDER *order); @@ -90,7 +89,7 @@ static ORDER *remove_const(JOIN *join,ORDER *first_order,COND *cond, bool change_list, bool *simple_order); static int return_zero_rows(JOIN *join, select_result *res,TABLE_LIST *tables, List<Item> &fields, bool send_row, - uint select_options, const char *info, + ulonglong select_options, const char *info, Item *having); static COND *build_equal_items(THD *thd, COND *cond, COND_EQUAL *inherited, @@ -114,7 +113,7 @@ static bool resolve_nested_join (TABLE_LIST *table); static bool const_expression_in_where(COND *conds,Item *item, Item **comp_item); static bool open_tmp_table(TABLE *table); static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param, - ulong options); + ulonglong options); static int do_select(JOIN *join,List<Item> *fields,TABLE *tmp_table, Procedure *proc); @@ -1974,7 +1973,7 @@ bool mysql_select(THD *thd, Item ***rref_pointer_array, TABLE_LIST *tables, uint wild_num, List<Item> &fields, COND *conds, uint og_num, ORDER *order, ORDER *group, - Item *having, ORDER *proc_param, ulong select_options, + Item *having, ORDER *proc_param, ulonglong select_options, select_result *result, SELECT_LEX_UNIT *unit, SELECT_LEX *select_lex) { @@ -2306,8 +2305,18 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables, COND *conds, substitution of a const table the key value happens to be null then we can state that there are no matches for this equi-join. */ - if ((keyuse= s->keyuse) && *s->on_expr_ref) + if ((keyuse= s->keyuse) && *s->on_expr_ref && !s->embedding_map) { + /* + When performing an outer join operation if there are no matching rows + for the single row of the outer table all the inner tables are to be + null complemented and thus considered as constant tables. + Here we apply this consideration to the case of outer join operations + with a single inner table only because the case with nested tables + would require a more thorough analysis. + TODO. Apply single row substitution to null complemented inner tables + for nested outer join operations. + */ while (keyuse->table == table) { if (!(keyuse->val->used_tables() & ~join->const_table_map) && @@ -4123,7 +4132,7 @@ choose_plan(JOIN *join, table_map join_tables) { uint search_depth= join->thd->variables.optimizer_search_depth; uint prune_level= join->thd->variables.optimizer_prune_level; - bool straight_join= join->select_options & SELECT_STRAIGHT_JOIN; + bool straight_join= test(join->select_options & SELECT_STRAIGHT_JOIN); DBUG_ENTER("choose_plan"); join->cur_embedding_map= 0; @@ -4725,8 +4734,6 @@ static void find_best(JOIN *join,table_map rest_tables,uint idx,double record_count, double read_time) { - ha_rows rec; - double tmp; THD *thd= join->thd; if (!rest_tables) { @@ -5780,7 +5787,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond) } static void -make_join_readinfo(JOIN *join, uint options) +make_join_readinfo(JOIN *join, ulonglong options) { uint i; @@ -6435,7 +6442,7 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond, static int return_zero_rows(JOIN *join, select_result *result,TABLE_LIST *tables, - List<Item> &fields, bool send_row, uint select_options, + List<Item> &fields, bool send_row, ulonglong select_options, const char *info, Item *having) { DBUG_ENTER("return_zero_rows"); @@ -6986,7 +6993,6 @@ static COND *build_equal_items_for_cond(COND *cond, Item_equal *item_equal; uint members; COND_EQUAL cond_equal; - COND *new_cond; cond_equal.upper_levels= inherited; if (cond->type() == Item::COND_ITEM) @@ -8436,6 +8442,46 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) return cond; // Point at next and level } +/* + Check if equality can be used in removing components of GROUP BY/DISTINCT + + SYNOPSIS + test_if_equality_guarantees_uniqueness() + l the left comparison argument (a field if any) + r the right comparison argument (a const of any) + + DESCRIPTION + Checks if an equality predicate can be used to take away + DISTINCT/GROUP BY because it is known to be true for exactly one + distinct value (e.g. <expr> == <const>). + Arguments must be of the same type because e.g. + <string_field> = <int_const> may match more than 1 distinct value from + the column. + We must take into consideration and the optimization done for various + string constants when compared to dates etc (see Item_int_with_ref) as + well as the collation of the arguments. + + RETURN VALUE + TRUE can be used + FALSE cannot be used +*/ +static bool +test_if_equality_guarantees_uniqueness(Item *l, Item *r) +{ + return r->const_item() && + /* elements must be of the same result type */ + (r->result_type() == l->result_type() || + /* or dates compared to longs */ + (((l->type() == Item::FIELD_ITEM && + ((Item_field *)l)->field->can_be_compared_as_longlong()) || + (l->type() == Item::FUNC_ITEM && + ((Item_func *)l)->result_as_longlong())) && + r->result_type() == INT_RESULT)) + /* and must have the same collation if compared as strings */ + && (l->result_type() != STRING_RESULT || + l->collation.collation == r->collation.collation); +} + /* Return 1 if the item is a const value in all the WHERE clause */ @@ -8472,7 +8518,7 @@ const_expression_in_where(COND *cond, Item *comp_item, Item **const_item) Item *right_item= ((Item_func*) cond)->arguments()[1]; if (left_item->eq(comp_item,1)) { - if (right_item->const_item()) + if (test_if_equality_guarantees_uniqueness (left_item, right_item)) { if (*const_item) return right_item->eq(*const_item, 1); @@ -8482,7 +8528,7 @@ const_expression_in_where(COND *cond, Item *comp_item, Item **const_item) } else if (right_item->eq(comp_item,1)) { - if (left_item->const_item()) + if (test_if_equality_guarantees_uniqueness (right_item, left_item)) { if (*const_item) return left_item->eq(*const_item, 1); @@ -9320,13 +9366,14 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields, param->recinfo=recinfo; store_record(table,s->default_values); // Make empty default record - if (thd->variables.tmp_table_size == ~(ulong) 0) // No limit + if (thd->variables.tmp_table_size == ~ (ulonglong) 0) // No limit table->s->max_rows= ~(ha_rows) 0; else - table->s->max_rows= (((table->s->db_type == DB_TYPE_HEAP) ? - min(thd->variables.tmp_table_size, - thd->variables.max_heap_table_size) : - thd->variables.tmp_table_size)/ table->s->reclength); + table->s->max_rows= (ha_rows) (((table->s->db_type == DB_TYPE_HEAP) ? + min(thd->variables.tmp_table_size, + thd->variables.max_heap_table_size) : + thd->variables.tmp_table_size)/ + table->s->reclength); set_if_bigger(table->s->max_rows,1); // For dummy start options /* Push the LIMIT clause to the temporary table creation, so that we @@ -9628,7 +9675,7 @@ static bool open_tmp_table(TABLE *table) static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param, - ulong options) + ulonglong options) { int error; MI_KEYDEF keydef; @@ -10387,6 +10434,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab, */ join->examined_rows++; join->thd->row_count++; + join_tab->read_record.file->unlock_row(); } return NESTED_LOOP_OK; } |