/* Copyright (C) 2002-2003 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. 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ /* Derived tables These were introduced by Sinisa */ #include "mysql_priv.h" #include "sql_select.h" /* Call given derived table processor (preparing or filling tables) SYNOPSIS mysql_handle_derived() lex LEX for this thread processor procedure of derived table processing RETURN FALSE OK TRUE Error */ bool mysql_handle_derived(LEX *lex, bool (*processor)(THD*, LEX*, TABLE_LIST*)) { bool res= FALSE; if (lex->derived_tables) { lex->thd->derived_tables_processing= TRUE; for (SELECT_LEX *sl= lex->all_selects_list; sl; sl= sl->next_select_in_list()) { for (TABLE_LIST *cursor= sl->get_table_list(); cursor; cursor= cursor->next_local) { if ((res= (*processor)(lex->thd, lex, cursor))) goto out; } if (lex->describe) { /* Force join->join_tmp creation, because we will use this JOIN twice for EXPLAIN and we have to have unchanged join for EXPLAINing */ sl->uncacheable|= UNCACHEABLE_EXPLAIN; sl->master_unit()->uncacheable|= UNCACHEABLE_EXPLAIN; } } } out: lex->thd->derived_tables_processing= FALSE; return res; } /* Create temporary table structure (but do not fill it) SYNOPSIS mysql_derived_prepare() thd Thread handle lex LEX for this thread orig_table_list TABLE_LIST for the upper SELECT IMPLEMENTATION Derived table is resolved with temporary table. After table creation, the above TABLE_LIST is updated with a new table. This function is called before any command containing derived table is executed. Derived tables is stored in thd->derived_tables and freed in close_thread_tables() RETURN FALSE OK TRUE Error */ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list) { SELECT_LEX_UNIT *unit= orig_table_list->derived; ulonglong create_options; DBUG_ENTER("mysql_derived_prepare"); bool res= FALSE; if (unit) { SELECT_LEX *first_select= unit->first_select(); TABLE *table= 0; select_union *derived_result; bool is_union= first_select->next_select() && first_select->next_select()->linkage == UNION_TYPE; /* prevent name resolving out of derived table */ for (SELECT_LEX *sl= first_select; sl; sl= sl->next_select()) sl->context.outer_context= 0; if (!(derived_result= new select_union)) DBUG_RETURN(TRUE); // out of memory // st_select_lex_unit::prepare correctly work for single select if ((res= unit->prepare(thd, derived_result, 0))) goto exit; if ((res= check_duplicate_names(unit->types, 0))) goto exit; create_options= (first_select->options | thd->options | TMP_TABLE_ALL_COLUMNS); /* Temp table is created so that it hounours if UNION without ALL is to be processed As 'distinct' parameter we always pass FALSE (0), because underlying query will control distinct condition by itself. Correct test of distinct underlying query will be is_union && !unit->union_distinct->next_select() (i.e. it is union and last distinct SELECT is last SELECT of UNION). */ if ((res= derived_result->create_result_table(thd, &unit->types, FALSE, create_options, orig_table_list->alias))) goto exit; table= derived_result->table; exit: /* Hide "Unknown column" or "Unknown function" error */ if (orig_table_list->view) { if (thd->net.last_errno == ER_BAD_FIELD_ERROR || thd->net.last_errno == ER_SP_DOES_NOT_EXIST) { thd->clear_error(); my_error(ER_VIEW_INVALID, MYF(0), orig_table_list->db, orig_table_list->table_name); } } /* if it is preparation PS only or commands that need only VIEW structure then we do not need real data and we can skip execution (and parameters is not defined, too) */ if (res) { if (table) free_tmp_table(thd, table); delete derived_result; } else { if (!thd->fill_derived_tables()) { delete derived_result; derived_result= NULL; } orig_table_list->derived_result= derived_result; orig_table_list->table= table; orig_table_list->table_name= (char*) table->s->table_name; orig_table_list->table_name_length= strlen((char*)table->s->table_name); table->derived_select_number= first_select->select_number; table->s->tmp_table= TMP_TABLE; #ifndef NO_EMBEDDED_ACCESS_CHECKS if (orig_table_list->referencing_view) table->grant= orig_table_list->grant; else table->grant.privilege= SELECT_ACL; #endif orig_table_list->db= (char *)""; orig_table_list->db_length= 0; // Force read of table stats in the optimizer table->file->info(HA_STATUS_VARIABLE); /* Add new temporary table to list of open derived tables */ table->next= thd->derived_tables; thd->derived_tables= table; } } else if (orig_table_list->merge_underlying_list) orig_table_list->set_underlying_merge(); DBUG_RETURN(res); } /* fill derived table SYNOPSIS mysql_derived_filling() thd Thread handle lex LEX for this thread unit node that contains all SELECT's for derived tables orig_table_list TABLE_LIST for the upper SELECT IMPLEMENTATION Derived table is resolved with temporary table. It is created based on the queries defined. After temporary table is filled, if this is not EXPLAIN, then the entire unit / node is deleted. unit is deleted if UNION is used for derived table and node is deleted is it is a simple SELECT. If you use this function, make sure it's not called at prepare. Due to evaluation of LIMIT clause it can not be used at prepared stage. RETURN FALSE OK TRUE Error */ bool mysql_derived_filling(THD *thd, LEX *lex, TABLE_LIST *orig_table_list) { TABLE *table= orig_table_list->table; SELECT_LEX_UNIT *unit= orig_table_list->derived; bool res= FALSE; /*check that table creation pass without problem and it is derived table */ if (table && unit) { SELECT_LEX *first_select= unit->first_select(); select_union *derived_result= orig_table_list->derived_result; SELECT_LEX *save_current_select= lex->current_select; bool is_union= first_select->next_select() && first_select->next_select()->linkage == UNION_TYPE; if (is_union) { // execute union without clean up res= unit->exec(); } else { unit->set_limit(first_select); if (unit->select_limit_cnt == HA_POS_ERROR) first_select->options&= ~OPTION_FOUND_ROWS; lex->current_select= first_select; res= mysql_select(thd, &first_select->ref_pointer_array, (TABLE_LIST*) first_select->table_list.first, first_select->with_wild, first_select->item_list, first_select->where, (first_select->order_list.elements+ first_select->group_list.elements), (ORDER *) first_select->order_list.first, (ORDER *) first_select->group_list.first, first_select->having, (ORDER*) NULL, (first_select->options | thd->options | SELECT_NO_UNLOCK), derived_result, unit, first_select); } if (!res) { /* Here we entirely fix both TABLE_LIST and list of SELECT's as there were no derived tables */ if (derived_result->flush()) res= TRUE; if (!lex->describe) unit->cleanup(); } else unit->cleanup(); lex->current_select= save_current_select; } return res; }