diff options
Diffstat (limited to 'sql/sql_union.cc')
| -rw-r--r-- | sql/sql_union.cc | 107 |
1 files changed, 93 insertions, 14 deletions
diff --git a/sql/sql_union.cc b/sql/sql_union.cc index 374e92c6a52..68419708182 100644 --- a/sql/sql_union.cc +++ b/sql/sql_union.cc @@ -105,6 +105,7 @@ bool select_union::flush() options create options table_alias name of the temporary table bit_fields_as_long convert bit fields to ulonglong + create_table whether to physically create result table DESCRIPTION Create a temporary table that is used to store the result of a UNION, @@ -119,7 +120,7 @@ bool select_union::create_result_table(THD *thd_arg, List<Item> *column_types, bool is_union_distinct, ulonglong options, const char *alias, - bool bit_fields_as_long) + bool bit_fields_as_long, bool create_table) { DBUG_ASSERT(table == 0); tmp_table_param.init(); @@ -128,10 +129,14 @@ select_union::create_result_table(THD *thd_arg, List<Item> *column_types, if (! (table= create_tmp_table(thd_arg, &tmp_table_param, *column_types, (ORDER*) 0, is_union_distinct, 1, - options, HA_POS_ERROR, (char*) alias))) + options, HA_POS_ERROR, (char*) alias, + !create_table))) return TRUE; - table->file->extra(HA_EXTRA_WRITE_CACHE); - table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); + if (create_table) + { + table->file->extra(HA_EXTRA_WRITE_CACHE); + table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); + } return FALSE; } @@ -285,6 +290,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, (is_union_select ? (ORDER*) 0 : (ORDER*) thd_arg->lex->proc_list.first), sl, this); + /* There are no * in the statement anymore (for PS) */ sl->with_wild= 0; last_procedure= join->procedure; @@ -347,6 +353,8 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, List_iterator_fast<Item> tp(types); Item *type; ulonglong create_options; + uint save_tablenr; + table_map save_map; while ((type= tp++)) { @@ -399,12 +407,22 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, create_options= create_options | TMP_TABLE_FORCE_MYISAM; if (union_result->create_result_table(thd, &types, test(union_distinct), - create_options, "", FALSE)) + create_options, "", FALSE, TRUE)) goto err; + if (fake_select_lex && !fake_select_lex->first_cond_optimization) + { + save_tablenr= result_table_list.tablenr_exec; + save_map= result_table_list.map_exec; + } bzero((char*) &result_table_list, sizeof(result_table_list)); result_table_list.db= (char*) ""; result_table_list.table_name= result_table_list.alias= (char*) "union"; result_table_list.table= table= union_result->table; + if (fake_select_lex && !fake_select_lex->first_cond_optimization) + { + result_table_list.tablenr_exec= save_tablenr; + result_table_list.map_exec= save_map; + } thd_arg->lex->current_select= lex_select_save; if (!item_list.elements) @@ -469,18 +487,21 @@ err: } -bool st_select_lex_unit::exec() +/** + Run optimization phase. + + @return FALSE unit successfully passed optimization phase. + @return TRUE an error occur. +*/ +bool st_select_lex_unit::optimize() { SELECT_LEX *lex_select_save= thd->lex->current_select; SELECT_LEX *select_cursor=first_select(); - ulonglong add_rows=0; - ha_rows examined_rows= 0; - DBUG_ENTER("st_select_lex_unit::exec"); + DBUG_ENTER("st_select_lex_unit::optimize"); - if (executed && !uncacheable && !describe) + if (optimized && !uncacheable && !describe) DBUG_RETURN(FALSE); - executed= 1; - + if (uncacheable || !item || !item->assigned() || describe) { if (item) @@ -501,7 +522,6 @@ bool st_select_lex_unit::exec() } for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select()) { - ha_rows records_at_start= 0; thd->lex->current_select= sl; if (optimized) @@ -528,6 +548,66 @@ bool st_select_lex_unit::exec() sl->join->select_options= (select_limit_cnt == HA_POS_ERROR || sl->braces) ? sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; + + saved_error= sl->join->optimize(); + } + + if (saved_error) + { + thd->lex->current_select= lex_select_save; + DBUG_RETURN(saved_error); + } + } + } + optimized= 1; + + thd->lex->current_select= lex_select_save; + DBUG_RETURN(saved_error); +} + + +bool st_select_lex_unit::exec() +{ + SELECT_LEX *lex_select_save= thd->lex->current_select; + SELECT_LEX *select_cursor=first_select(); + ulonglong add_rows=0; + ha_rows examined_rows= 0; + DBUG_ENTER("st_select_lex_unit::exec"); + + if (executed && !uncacheable && !describe) + DBUG_RETURN(FALSE); + executed= 1; + + saved_error= optimize(); + + if (uncacheable || !item || !item->assigned() || describe) + { + for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select()) + { + ha_rows records_at_start= 0; + thd->lex->current_select= sl; + + { + set_limit(sl); + if (sl == global_parameters || describe) + { + offset_limit_cnt= 0; + /* + We can't use LIMIT at this stage if we are using ORDER BY for the + whole query + */ + if (sl->order_list.first || describe) + select_limit_cnt= HA_POS_ERROR; + } + + /* + When using braces, SQL_CALC_FOUND_ROWS affects the whole query: + we don't calculate found_rows() per union part. + Otherwise, SQL_CALC_FOUND_ROWS should be done on all sub parts. + */ + sl->join->select_options= + (select_limit_cnt == HA_POS_ERROR || sl->braces) ? + sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; saved_error= sl->join->optimize(); } if (!saved_error) @@ -580,7 +660,6 @@ bool st_select_lex_unit::exec() } } } - optimized= 1; /* Send result to 'result' */ saved_error= TRUE; |