diff options
Diffstat (limited to 'sql/sql_union.cc')
| -rw-r--r-- | sql/sql_union.cc | 176 |
1 files changed, 106 insertions, 70 deletions
diff --git a/sql/sql_union.cc b/sql/sql_union.cc index 556493f4fc8..951248e8cd8 100644 --- a/sql/sql_union.cc +++ b/sql/sql_union.cc @@ -23,6 +23,7 @@ #include "mysql_priv.h" #include "sql_select.h" +#include "sql_cursor.h" bool mysql_union(THD *thd, LEX *lex, select_result *result, SELECT_LEX_UNIT *unit, ulong setup_tables_done_option) @@ -30,13 +31,9 @@ bool mysql_union(THD *thd, LEX *lex, select_result *result, DBUG_ENTER("mysql_union"); bool res; if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK | - setup_tables_done_option, ""))) + setup_tables_done_option))) res= unit->exec(); - if (!res && thd->cursor && thd->cursor->is_open()) - { - thd->cursor->set_unit(unit); - } - else + if (res || !thd->cursor || !thd->cursor->is_open()) res|= unit->cleanup(); DBUG_RETURN(res); } @@ -46,16 +43,6 @@ bool mysql_union(THD *thd, LEX *lex, select_result *result, ** store records in temporary table for UNION ***************************************************************************/ -select_union::select_union(TABLE *table_par) - :table(table_par) -{ -} - -select_union::~select_union() -{ -} - - int select_union::prepare(List<Item> &list, SELECT_LEX_UNIT *u) { unit= u; @@ -103,6 +90,45 @@ bool select_union::flush() return 0; } +/* + Create a temporary table to store the result of select_union. + + SYNOPSIS + select_union::create_result_table() + thd thread handle + column_types a list of items used to define columns of the + temporary table + is_union_distinct if set, the temporary table will eliminate + duplicates on insert + options create options + + DESCRIPTION + Create a temporary table that is used to store the result of a UNION, + derived table, or a materialized cursor. + + RETURN VALUE + 0 The table has been created successfully. + 1 create_tmp_table failed. +*/ + +bool +select_union::create_result_table(THD *thd, List<Item> *column_types, + bool is_union_distinct, ulonglong options, + const char *alias) +{ + DBUG_ASSERT(table == 0); + tmp_table_param.init(); + tmp_table_param.field_count= column_types->elements; + + if (! (table= create_tmp_table(thd, &tmp_table_param, *column_types, + (ORDER*) 0, is_union_distinct, 1, + options, HA_POS_ERROR, (char*) alias))) + return TRUE; + table->file->extra(HA_EXTRA_WRITE_CACHE); + table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); + return FALSE; +} + /* initialization procedures before fake_select_lex preparation() @@ -133,11 +159,10 @@ st_select_lex_unit::init_prepare_fake_select_lex(THD *thd) bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, - ulong additional_options, - const char *tmp_table_alias) + ulong additional_options) { SELECT_LEX *lex_select_save= thd_arg->lex->current_select; - SELECT_LEX *sl, *first_select; + SELECT_LEX *sl, *first_sl= first_select(); select_result *tmp_result; bool is_union; TABLE *empty_table= 0; @@ -156,7 +181,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, if (describe) { /* fast reinit for EXPLAIN */ - for (sl= first_select_in_union(); sl; sl= sl->next_select()) + for (sl= first_sl; sl; sl= sl->next_select()) { sl->join->result= result; select_limit_cnt= HA_POS_ERROR; @@ -175,17 +200,16 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, prepared= 1; res= FALSE; - thd_arg->lex->current_select= sl= first_select= first_select_in_union(); - found_rows_for_union= first_select->options & OPTION_FOUND_ROWS; - is_union= test(first_select->next_select()); + thd_arg->lex->current_select= sl= first_sl; + found_rows_for_union= first_sl->options & OPTION_FOUND_ROWS; + is_union= test(first_sl->next_select()); /* Global option */ if (is_union) { - if (!(tmp_result= union_result= new select_union(0))) + if (!(tmp_result= union_result= new select_union)) goto err; - union_result->tmp_table_param.init(); if (describe) tmp_result= sel_result; } @@ -238,8 +262,8 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, information about fields lengths and exact types */ if (!is_union) - types= first_select_in_union()->item_list; - else if (sl == first_select) + types= first_sl->item_list; + else if (sl == first_sl) { /* We need to create an empty table object. It is used @@ -287,7 +311,6 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, all collations together for UNION. */ List_iterator_fast<Item> tp(types); - Query_arena *arena= thd->stmt_arena; Item *type; ulonglong create_options; @@ -301,7 +324,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, } } - create_options= (first_select_in_union()->options | thd_arg->options | + create_options= (first_sl->options | thd_arg->options | TMP_TABLE_ALL_COLUMNS); /* Force the temporary table to be a MyISAM table if we're going to use @@ -312,47 +335,35 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, if (global_parameters->ftfunc_list->elements) create_options= create_options | TMP_TABLE_FORCE_MYISAM; - union_result->tmp_table_param.field_count= types.elements; - if (!(table= create_tmp_table(thd_arg, - &union_result->tmp_table_param, types, - (ORDER*) 0, (bool) union_distinct, 1, - create_options, HA_POS_ERROR, - (char *) tmp_table_alias))) + if (union_result->create_result_table(thd, &types, test(union_distinct), + create_options, "")) goto err; - table->file->extra(HA_EXTRA_WRITE_CACHE); - table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); 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->set_table(table); + result_table_list.table= table= union_result->table; thd_arg->lex->current_select= lex_select_save; if (!item_list.elements) { - Field **field; - Query_arena *tmp_arena,backup; - tmp_arena= thd->activate_stmt_arena_if_needed(&backup); + Query_arena *arena, backup_arena; - for (field= table->field; *field; field++) - { - Item_field *item= new Item_field(*field); - if (!item || item_list.push_back(item)) - { - if (tmp_arena) - thd->restore_active_arena(tmp_arena, &backup); - DBUG_RETURN(TRUE); - } - } - if (tmp_arena) - thd->restore_active_arena(tmp_arena, &backup); - if (arena->is_stmt_prepare_or_first_sp_execute()) + arena= thd->activate_stmt_arena_if_needed(&backup_arena); + + res= table->fill_item_list(&item_list); + + if (arena) + thd->restore_active_arena(arena, &backup_arena); + + if (res) + goto err; + + if (thd->stmt_arena->is_stmt_prepare()) { - /* prepare fake select to initialize it correctly */ + /* Validate the global parameters of this union */ + init_prepare_fake_select_lex(thd); - /* - Should be done only once (the only item_list per statement). - */ + /* Should be done only once (the only item_list per statement) */ DBUG_ASSERT(fake_select_lex->join == 0); if (!(fake_select_lex->join= new JOIN(thd, item_list, thd->options, result))) @@ -375,19 +386,14 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result, fake_select_lex->table_list.empty(); } } - else if (!arena->is_conventional()) + else { + DBUG_ASSERT(!thd->stmt_arena->is_conventional()); /* We're in execution of a prepared statement or stored procedure: reset field items to point at fields from the created temporary table. */ - List_iterator_fast<Item> it(item_list); - for (Field **field= table->field; *field; field++) - { - Item_field *item_field= (Item_field*) it++; - DBUG_ASSERT(item_field != 0); - item_field->reset_field(*field); - } + table->reset_item_list(&item_list); } } @@ -404,7 +410,7 @@ err: bool st_select_lex_unit::exec() { SELECT_LEX *lex_select_save= thd->lex->current_select; - SELECT_LEX *select_cursor=first_select_in_union(); + SELECT_LEX *select_cursor=first_select(); ulonglong add_rows=0; ha_rows examined_rows= 0; DBUG_ENTER("st_select_lex_unit::exec"); @@ -595,7 +601,7 @@ bool st_select_lex_unit::cleanup() table= 0; // Safety } - for (SELECT_LEX *sl= first_select_in_union(); sl; sl= sl->next_select()) + for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) error|= sl->cleanup(); if (fake_select_lex) @@ -652,7 +658,7 @@ bool st_select_lex_unit::change_result(select_subselect *result, select_subselect *old_result) { bool res= FALSE; - for (SELECT_LEX *sl= first_select_in_union(); sl; sl= sl->next_select()) + for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) { if (sl->join && sl->join->result == old_result) if (sl->join->change_result(result)) @@ -663,6 +669,36 @@ bool st_select_lex_unit::change_result(select_subselect *result, return (res); } +/* + Get column type information for this unit. + + SYNOPSIS + st_select_lex_unit::get_unit_column_types() + + DESCRIPTION + For a single-select the column types are taken + from the list of selected items. For a union this function + assumes that st_select_lex_unit::prepare has been called + and returns the type holders that were created for unioned + column types of all selects. + + NOTES + The implementation of this function should be in sync with + st_select_lex_unit::prepare() +*/ + +List<Item> *st_select_lex_unit::get_unit_column_types() +{ + bool is_union= test(first_select()->next_select()); + + if (is_union) + { + DBUG_ASSERT(prepared); + /* Types are generated during prepare */ + return &types; + } + return &first_select()->item_list; +} bool st_select_lex::cleanup() { |