/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. Copyright (c) 2010, 2020, MariaDB Corporation. 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 St, Fifth Floor, Boston, MA 02110-1335 USA */ /* UNION of select's UNION's were introduced by Monty and Sinisa */ #include "mariadb.h" #include "sql_priv.h" #include "unireg.h" #include "sql_union.h" #include "sql_select.h" #include "sql_cursor.h" #include "sql_base.h" // fill_record #include "filesort.h" // filesort_free_buffers #include "sql_view.h" #include "sql_cte.h" bool mysql_union(THD *thd, LEX *lex, select_result *result, SELECT_LEX_UNIT *unit, ulong setup_tables_done_option) { DBUG_ENTER("mysql_union"); bool res; if (!(res= unit->prepare(unit->derived, result, SELECT_NO_UNLOCK | setup_tables_done_option))) res= unit->exec(); res|= unit->cleanup(); DBUG_RETURN(res); } /*************************************************************************** ** store records in temporary table for UNION ***************************************************************************/ int select_unit::prepare(List &list, SELECT_LEX_UNIT *u) { unit= u; return 0; } /** This called by SELECT_LEX_UNIT::exec when select changed */ void select_unit::change_select() { uint current_select_number= thd->lex->current_select->select_number; DBUG_ENTER("select_unit::change_select"); DBUG_PRINT("enter", ("select in unit change: %u -> %u", curr_sel, current_select_number)); DBUG_ASSERT(curr_sel != current_select_number); curr_sel= current_select_number; /* New SELECT processing starts */ DBUG_ASSERT(table->file->inited == 0); step= thd->lex->current_select->get_linkage(); switch (step) { case INTERSECT_TYPE: prev_step= curr_step; curr_step= current_select_number; break; case EXCEPT_TYPE: break; default: step= UNION_TYPE; break; } DBUG_VOID_RETURN; } /** Fill temporary tables for UNION/EXCEPT/INTERSECT @Note UNION: just add records to the table (with 'counter' field first if INTERSECT present in the sequence). EXCEPT: looks for the record in the table (with 'counter' field first if INTERSECT present in the sequence) and delete it if found INTERSECT: looks for the same record with 'counter' field of previous operation, put as a 'counter' number of the current SELECT. We scan the table and remove all records which marked with not last 'counter' after processing all records in send_eof and only if it last SELECT of sequence of INTERSECTS. @param values List of record items to process. @retval 0 - OK @retval -1 - duplicate @retval 1 - error */ int select_unit::send_data(List &values) { int rc= 0; int not_reported_error= 0; if (table->no_rows_with_nulls) table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT; fill_record(thd, table, table->field + addon_cnt, values, true, false); /* set up initial values for records to be written */ if (addon_cnt && step == UNION_TYPE) { DBUG_ASSERT(addon_cnt == 1); table->field[0]->store((longlong) curr_step, 1); } if (unlikely(thd->is_error())) { rc= 1; if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } if (table->no_rows_with_nulls) { table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT; if (table->null_catch_flags) { rc= 0; if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } } /* select_unit::change_select() change step & Co correctly for each SELECT */ int find_res; switch (step) { case UNION_TYPE: rc= write_record(); /* no reaction with conversion */ if (rc == -2) rc= 0; break; case EXCEPT_TYPE: /* The temporary table uses very first index or constrain for checking unique constrain. */ if (!(find_res= table->file->find_unique_row(table->record[0], 0))) rc= delete_record(); else rc= not_reported_error= (find_res != 1); break; case INTERSECT_TYPE: /* The temporary table uses very first index or constrain for checking unique constrain. */ if (!(find_res= table->file->find_unique_row(table->record[0], 0))) { DBUG_ASSERT(!table->triggers); if (table->field[0]->val_int() == prev_step) { not_reported_error= update_counter(table->field[0], curr_step); rc= MY_TEST(not_reported_error); DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME); } } else rc= not_reported_error= (find_res != 1); break; default: DBUG_ASSERT(0); } if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } bool select_unit::send_eof() { if (step != INTERSECT_TYPE || (thd->lex->current_select->next_select() && thd->lex->current_select->next_select()->get_linkage() == INTERSECT_TYPE)) { /* it is not INTERSECT or next SELECT in the sequence is INTERSECT so no need filtering (the last INTERSECT in this sequence of intersects will filter). */ return 0; } /* It is last select in the sequence of INTERSECTs so we should filter out all records except marked with actual counter. TODO: as optimization for simple case this could be moved to 'fake_select' WHERE condition */ int error; if (table->file->ha_rnd_init_with_error(1)) return 1; do { error= table->file->ha_rnd_next(table->record[0]); if (unlikely(error)) { if (error == HA_ERR_END_OF_FILE) { error= 0; break; } break; } if (table->field[0]->val_int() != curr_step) error= delete_record(); } while (!error); table->file->ha_rnd_end(); if (unlikely(error)) table->file->print_error(error, MYF(0)); return(MY_TEST(error)); } int select_union_recursive::send_data(List &values) { int rc= select_unit::send_data(values); if (rc == 0 && write_err != HA_ERR_FOUND_DUPP_KEY && write_err != HA_ERR_FOUND_DUPP_UNIQUE) { int err; DBUG_ASSERT(incr_table->s->reclength == table->s->reclength || incr_table->s->reclength == table->s->reclength - MARIA_UNIQUE_HASH_LENGTH); if ((err= incr_table->file->ha_write_tmp_row(table->record[0]))) { bool is_duplicate; rc= create_internal_tmp_table_from_heap(thd, incr_table, tmp_table_param.start_recinfo, &tmp_table_param.recinfo, err, 1, &is_duplicate); } } return rc; } bool select_unit::flush() { int error; if (unlikely((error=table->file->extra(HA_EXTRA_NO_CACHE)))) { table->file->print_error(error, MYF(0)); return 1; } return 0; } /* Create a temporary table to store the result of select_union. SYNOPSIS select_unit::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 table_alias name of the temporary table bit_fields_as_long convert bit fields to ulonglong create_table whether to physically create result table keep_row_order keep rows in order as they were inserted hidden number of hidden fields (for INTERSECT) plus one for `ALL` 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_unit::create_result_table(THD *thd_arg, List *column_types, bool is_union_distinct, ulonglong options, const LEX_CSTRING *alias, bool bit_fields_as_long, bool create_table, bool keep_row_order, uint hidden) { DBUG_ASSERT(table == 0); tmp_table_param.init(); tmp_table_param.field_count= column_types->elements; tmp_table_param.bit_fields_as_long= bit_fields_as_long; tmp_table_param.hidden_field_count= hidden; if (! (table= create_tmp_table(thd_arg, &tmp_table_param, *column_types, (ORDER*) 0, is_union_distinct, 1, options, HA_POS_ERROR, alias, !create_table, keep_row_order))) return TRUE; table->keys_in_use_for_query.clear_all(); for (uint i=0; i < table->s->fields; i++) table->field[i]->flags &= ~(PART_KEY_FLAG | PART_INDIRECT_KEY_FLAG); if (create_table) { table->file->extra(HA_EXTRA_WRITE_CACHE); table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); } return FALSE; } bool select_union_recursive::create_result_table(THD *thd_arg, List *column_types, bool is_union_distinct, ulonglong options, const LEX_CSTRING *alias, bool bit_fields_as_long, bool create_table, bool keep_row_order, uint hidden) { if (select_unit::create_result_table(thd_arg, column_types, is_union_distinct, options, &empty_clex_str, bit_fields_as_long, create_table, keep_row_order, hidden)) return true; incr_table_param.init(); incr_table_param.field_count= column_types->elements; incr_table_param.bit_fields_as_long= bit_fields_as_long; if (! (incr_table= create_tmp_table(thd_arg, &incr_table_param, *column_types, (ORDER*) 0, false, 1, options, HA_POS_ERROR, &empty_clex_str, true, keep_row_order))) return true; incr_table->keys_in_use_for_query.clear_all(); for (uint i=0; i < table->s->fields; i++) incr_table->field[i]->flags &= ~(PART_KEY_FLAG | PART_INDIRECT_KEY_FLAG); return false; } /* @brief Write a record @retval -2 conversion happened -1 found a duplicate key 0 no error 1 if an error is reported */ int select_unit::write_record() { if (unlikely((write_err= table->file->ha_write_tmp_row(table->record[0])))) { if (write_err == HA_ERR_FOUND_DUPP_KEY) { /* Inform upper level that we found a duplicate key, that should not be counted as part of limit */ return -1; } bool is_duplicate= false; /* create_internal_tmp_table_from_heap will generate error if needed */ if (table->file->is_fatal_error(write_err, HA_CHECK_DUP)) { if (!create_internal_tmp_table_from_heap(thd, table, tmp_table_param.start_recinfo, &tmp_table_param.recinfo, write_err, 1, &is_duplicate)) { return -2; } else { return 1; } } if (is_duplicate) { return -1; } } return 0; } /* @brief Update counter for a record @retval 0 no error -1 error occurred */ int select_unit::update_counter(Field* counter, longlong value) { store_record(table, record[1]); counter->store(value, 0); int error= table->file->ha_update_tmp_row(table->record[1], table->record[0]); return error; } /* @brief Try to disable index @retval true index is disabled this time false this time did not disable the index */ bool select_unit_ext::disable_index_if_needed(SELECT_LEX *curr_sl) { if (is_index_enabled && (curr_sl == curr_sl->master_unit()->union_distinct || !curr_sl->next_select()) ) { is_index_enabled= false; if (table->file->ha_disable_indexes(HA_KEY_SWITCH_ALL)) return false; table->no_keyread=1; return true; } return false; } /* @brief Unfold a record @retval 0 no error -1 conversion happened */ int select_unit_ext::unfold_record(ha_rows cnt) { DBUG_ASSERT(cnt > 0); int error= 0; bool is_convertion_happened= false; while (--cnt) { error= write_record(); if (error == -2) { is_convertion_happened= true; error= -1; } } if (is_convertion_happened) return -1; return error; } /* @brief Delete a record @retval 0 no error 1 if an error is reported */ int select_unit::delete_record() { DBUG_ASSERT(!table->triggers); table->status|= STATUS_DELETED; int not_reported_error= table->file->ha_delete_tmp_row(table->record[0]); return MY_TEST(not_reported_error); } /** Reset and empty the temporary table that stores the materialized query result. @note The cleanup performed here is exactly the same as for the two temp tables of JOIN - exec_tmp_table_[1 | 2]. */ void select_unit::cleanup() { table->file->extra(HA_EXTRA_RESET_STATE); table->file->ha_delete_all_rows(); } /* @brief Set up value needed by send_data() and send_eof() @detail - For EXCEPT we will decrease the counter by one and INTERSECT / UNION we increase the counter. - For INTERSECT we will modify the second extra field (intersect counter) and for EXCEPT / UNION we modify the first (duplicate counter) */ void select_unit_ext::change_select() { select_unit::change_select(); switch(step){ case UNION_TYPE: increment= 1; curr_op_type= UNION_DISTINCT; break; case EXCEPT_TYPE: increment= -1; curr_op_type= EXCEPT_DISTINCT; break; case INTERSECT_TYPE: increment= 1; curr_op_type= INTERSECT_DISTINCT; break; default: DBUG_ASSERT(0); } if (!thd->lex->current_select->distinct) /* change type from DISTINCT to ALL */ curr_op_type= (set_op_type)(curr_op_type + 1); duplicate_cnt= table->field[addon_cnt - 1]; if (addon_cnt == 2) additional_cnt= table->field[addon_cnt - 2]; else additional_cnt= NULL; } /* @brief Fill temporary tables for operations need extra fields @detail - If this operation is not distinct, we try to find it and increase the counter by "increment" setted in select_unit_ext::change_select(). - If it is distinct, for UNION we write this record; for INTERSECT we try to find it and increase the intersect counter if found; for EXCEPT we try to find it and delete that record if found. */ int select_unit_ext::send_data(List &values) { int rc= 0; int not_reported_error= 0; int find_res; if (table->no_rows_with_nulls) table->null_catch_flags= CHECK_ROW_FOR_NULLS_TO_REJECT; fill_record(thd, table, table->field + addon_cnt, values, true, false); /* set up initial values for records to be written */ if ( step == UNION_TYPE ) { /* set duplicate counter to 1 */ duplicate_cnt->store((longlong) 1, 1); /* set the other counter to 0 */ if (curr_op_type == INTERSECT_ALL) additional_cnt->store((longlong) 0, 1); } if (unlikely(thd->is_error())) { rc= 1; if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } if (table->no_rows_with_nulls) { table->null_catch_flags&= ~CHECK_ROW_FOR_NULLS_TO_REJECT; if (table->null_catch_flags) { if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } } switch(curr_op_type) { case UNION_ALL: if (!is_index_enabled || (find_res= table->file->find_unique_row(table->record[0], 0))) { rc= write_record(); /* no reaction with conversion */ if (rc == -2) rc= 0; } else { longlong cnt= duplicate_cnt->val_int() + increment; not_reported_error= update_counter(duplicate_cnt, cnt); DBUG_ASSERT(!table->triggers); rc= MY_TEST(not_reported_error); } break; case EXCEPT_ALL: if (!(find_res= table->file->find_unique_row(table->record[0], 0))) { longlong cnt= duplicate_cnt->val_int() + increment; if (cnt == 0) rc= delete_record(); else { not_reported_error= update_counter(duplicate_cnt, cnt); DBUG_ASSERT(!table->triggers); rc= MY_TEST(not_reported_error); } } break; case INTERSECT_ALL: if (!(find_res= table->file->find_unique_row(table->record[0], 0))) { longlong cnt= duplicate_cnt->val_int() + increment; if (cnt <= additional_cnt->val_int()) { not_reported_error= update_counter(duplicate_cnt, cnt); DBUG_ASSERT(!table->triggers); rc= MY_TEST(not_reported_error); } } break; case UNION_DISTINCT: rc= write_record(); /* no reaction with conversion */ if (rc == -2) rc= 0; break; case EXCEPT_DISTINCT: if (!(find_res= table->file->find_unique_row(table->record[0], 0))) rc= delete_record(); else rc= not_reported_error= (find_res != 1); break; case INTERSECT_DISTINCT: if (!(find_res= table->file->find_unique_row(table->record[0], 0))) { if (additional_cnt->val_int() == prev_step) { not_reported_error= update_counter(additional_cnt, curr_step); rc= MY_TEST(not_reported_error); DBUG_ASSERT(rc != HA_ERR_RECORD_IS_THE_SAME); } else if (additional_cnt->val_int() != curr_step) rc= delete_record(); } else rc= not_reported_error= (find_res != 1); break; default: DBUG_ASSERT(0); } if (unlikely(not_reported_error)) { DBUG_ASSERT(rc); table->file->print_error(not_reported_error, MYF(0)); } return rc; } /* @brief Do post-operation after a operator @detail We need to scan in these cases: - If this operation is DISTINCT and next is ALL, duplicate counter needs to be set to 1. - If this operation is INTERSECT ALL and counter needs to be updated. - If next operation is INTERSECT ALL, set up the second extra field (called "intersect_counter") to 0. this extra field counts records in the second operand. If this operation is equal to "union_distinct" or is the last operation, we'll disable index. Then if this operation is ALL we'll unfold records. */ bool select_unit_ext::send_eof() { int error= 0; SELECT_LEX *curr_sl= thd->lex->current_select; SELECT_LEX *next_sl= curr_sl->next_select(); bool is_next_distinct= next_sl && next_sl->distinct; bool is_next_intersect_all= next_sl && next_sl->get_linkage() == INTERSECT_TYPE && !next_sl->distinct; bool need_unfold= (disable_index_if_needed(curr_sl) && !curr_sl->distinct); if (((curr_sl->distinct && !is_next_distinct) || curr_op_type == INTERSECT_ALL || is_next_intersect_all) && !need_unfold) { if (!next_sl) DBUG_ASSERT(curr_op_type != INTERSECT_ALL); bool need_update_row; if (unlikely(table->file->ha_rnd_init_with_error(1))) return 1; do { need_update_row= false; if (unlikely(error= table->file->ha_rnd_next(table->record[0]))) { if (error == HA_ERR_END_OF_FILE) { error= 0; break; } break; } store_record(table, record[1]); if (curr_sl->distinct && !is_next_distinct) { /* set duplicate counter to 1 if next operation is ALL */ duplicate_cnt->store(1, 0); need_update_row= true; } if (is_next_intersect_all) { longlong d_cnt_val= duplicate_cnt->val_int(); if (d_cnt_val == 0) error= delete_record(); else { if (curr_op_type == INTERSECT_ALL) { longlong a_cnt_val= additional_cnt->val_int(); if (a_cnt_val < d_cnt_val) d_cnt_val= a_cnt_val; } additional_cnt->store(d_cnt_val, 0); duplicate_cnt->store((longlong)0, 0); need_update_row= true; } } if (need_update_row) error= table->file->ha_update_tmp_row(table->record[1], table->record[0]); } while (likely(!error)); table->file->ha_rnd_end(); } /* unfold */ else if (need_unfold) { /* unfold if is ALL operation */ ha_rows dup_cnt; if (unlikely(table->file->ha_rnd_init_with_error(1))) return 1; do { if (unlikely(error= table->file->ha_rnd_next(table->record[0]))) { if (error == HA_ERR_END_OF_FILE) { error= 0; break; } break; } dup_cnt= (ha_rows)duplicate_cnt->val_int(); /* delete record if not exist in the second operand */ if (dup_cnt == 0) { error= delete_record(); continue; } if (curr_op_type == INTERSECT_ALL) { ha_rows add_cnt= (ha_rows)additional_cnt->val_int(); if (dup_cnt > add_cnt && add_cnt > 0) dup_cnt= (ha_rows)add_cnt; } if (dup_cnt == 1) continue; duplicate_cnt->store((longlong)1, 0); if (additional_cnt) additional_cnt->store((longlong)0, 0); error= table->file->ha_update_tmp_row(table->record[1], table->record[0]); if (unlikely(error)) break; if (unfold_record(dup_cnt) == -1) { /* restart the scan */ if (unlikely(table->file->ha_rnd_init_with_error(1))) return 1; duplicate_cnt= table->field[addon_cnt - 1]; if (addon_cnt == 2) additional_cnt= table->field[addon_cnt - 2]; else additional_cnt= NULL; continue; } } while (likely(!error)); table->file->ha_rnd_end(); } /* Clean up table buffers for the next set operation from pipeline */ if (next_sl) restore_record(table,s->default_values); if (unlikely(error)) table->file->print_error(error, MYF(0)); return (MY_TEST(error)); } void select_union_recursive::cleanup() { if (table) { select_unit::cleanup(); free_tmp_table(thd, table); } if (incr_table) { if (incr_table->is_created()) { incr_table->file->extra(HA_EXTRA_RESET_STATE); incr_table->file->ha_delete_all_rows(); } free_tmp_table(thd, incr_table); } List_iterator it(rec_table_refs); TABLE_LIST *tbl; while ((tbl= it++)) { TABLE *tab= tbl->table; if (tab->is_created()) { tab->file->extra(HA_EXTRA_RESET_STATE); tab->file->ha_delete_all_rows(); } /* The table will be closed later in close_thread_tables(), because it might be used in the statements like ANALYZE WITH r AS (...) SELECT * from r where r is defined through recursion. */ tab->next= thd->rec_tables; thd->rec_tables= tab; tbl->derived_result= 0; } } /** Replace the current result with new_result and prepare it. @param new_result New result pointer @retval FALSE Success @retval TRUE Error */ bool select_union_direct::change_result(select_result *new_result) { result= new_result; return (result->prepare(unit->types, unit) || result->prepare2(NULL)); } bool select_union_direct::postponed_prepare(List &types) { if (result != NULL) return (result->prepare(types, unit) || result->prepare2(NULL)); else return false; } bool select_union_direct::send_result_set_metadata(List &list, uint flags) { if (done_send_result_set_metadata) return false; done_send_result_set_metadata= true; /* Set global offset and limit to be used in send_data(). These can be variables in prepared statements or stored programs, so they must be reevaluated for each execution. */ offset= unit->global_parameters()->get_offset(); limit= unit->global_parameters()->get_limit(); if (limit + offset >= limit) limit+= offset; else limit= HA_POS_ERROR; /* purecov: inspected */ return result->send_result_set_metadata(unit->types, flags); } int select_union_direct::send_data(List &items) { if (!limit) return false; limit--; if (offset) { offset--; return false; } send_records++; fill_record(thd, table, table->field, items, true, false); if (unlikely(thd->is_error())) return true; /* purecov: inspected */ return result->send_data(unit->item_list); } bool select_union_direct::initialize_tables (JOIN *join) { if (done_initialize_tables) return false; done_initialize_tables= true; return result->initialize_tables(join); } bool select_union_direct::send_eof() { // Reset for each SELECT_LEX, so accumulate here limit_found_rows+= thd->limit_found_rows; if (unit->thd->lex->current_select == last_select_lex) { thd->limit_found_rows= limit_found_rows; // Reset and make ready for re-execution done_send_result_set_metadata= false; done_initialize_tables= false; return result->send_eof(); } else return false; } /* initialization procedures before fake_select_lex preparation() SYNOPSIS st_select_lex_unit::init_prepare_fake_select_lex() thd - thread handler first_execution - TRUE at the first execution of the union RETURN options of SELECT */ void st_select_lex_unit::init_prepare_fake_select_lex(THD *thd_arg, bool first_execution) { thd_arg->lex->current_select= fake_select_lex; fake_select_lex->table_list.link_in_list(&result_table_list, &result_table_list.next_local); fake_select_lex->context.table_list= fake_select_lex->context.first_name_resolution_table= fake_select_lex->get_table_list(); /* The flag fake_select_lex->first_execution indicates whether this is called at the first execution of the statement, while first_execution shows whether this is called at the first execution of the union that may form just a subselect. */ if ((fake_select_lex->changed_elements & TOUCHED_SEL_COND) && first_execution) { for (ORDER *order= global_parameters()->order_list.first; order; order= order->next) order->item= &order->item_ptr; } for (ORDER *order= global_parameters()->order_list.first; order; order=order->next) { (*order->item)->walk(&Item::change_context_processor, 0, &fake_select_lex->context); (*order->item)->walk(&Item::set_fake_select_as_master_processor, 0, fake_select_lex); } } bool st_select_lex_unit::prepare_join(THD *thd_arg, SELECT_LEX *sl, select_result *tmp_result, ulonglong additional_options, bool is_union_select) { DBUG_ENTER("st_select_lex_unit::prepare_join"); TABLE_LIST *derived= sl->master_unit()->derived; bool can_skip_order_by; sl->options|= SELECT_NO_UNLOCK; JOIN *join= new JOIN(thd_arg, sl->item_list, (sl->options | thd_arg->variables.option_bits | additional_options), tmp_result); if (!join) DBUG_RETURN(true); thd_arg->lex->current_select= sl; can_skip_order_by= (is_union_select && !(sl->braces && sl->limit_params.explicit_limit) && !thd->lex->with_rownum); saved_error= join->prepare(sl->table_list.first, (derived && derived->merged ? NULL : sl->where), (can_skip_order_by ? 0 : sl->order_list.elements) + sl->group_list.elements, can_skip_order_by ? NULL : sl->order_list.first, can_skip_order_by, sl->group_list.first, sl->having, (is_union_select ? NULL : thd_arg->lex->proc_list.first), sl, this); last_procedure= join->procedure; if (unlikely(saved_error || (saved_error= thd_arg->is_fatal_error))) DBUG_RETURN(true); /* Remove all references from the select_lex_units to the subqueries that are inside the ORDER BY clause. */ if (can_skip_order_by) { for (ORDER *ord= (ORDER *)sl->order_list.first; ord; ord= ord->next) { (*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL); } } DBUG_RETURN(false); } /** Aggregate data type handlers for the "count" leftmost UNION parts. */ bool st_select_lex_unit::join_union_type_handlers(THD *thd_arg, Type_holder *holders, uint count) { DBUG_ENTER("st_select_lex_unit::join_union_type_handlers"); SELECT_LEX *first_sl= first_select(), *sl= first_sl; for (uint i= 0; i < count ; sl= sl->next_select(), i++) { Item *item; List_iterator_fast it(sl->item_list); for (uint pos= 0; (item= it++); pos++) { const Type_handler *item_type_handler= item->real_type_handler(); if (sl == first_sl) holders[pos].set_handler(item_type_handler); else { DBUG_ASSERT(first_sl->item_list.elements == sl->item_list.elements); if (holders[pos].aggregate_for_result(item_type_handler)) { my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0), holders[pos].type_handler()->name().ptr(), item_type_handler->name().ptr(), "UNION"); DBUG_RETURN(true); } } } } DBUG_RETURN(false); } /** Aggregate data type attributes for the "count" leftmost UNION parts. */ bool st_select_lex_unit::join_union_type_attributes(THD *thd_arg, Type_holder *holders, uint count) { DBUG_ENTER("st_select_lex_unit::join_union_type_attributes"); SELECT_LEX *sl, *first_sl= first_select(); uint item_pos; for (uint pos= 0; pos < first_sl->item_list.elements; pos++) { if (holders[pos].alloc_arguments(thd_arg, count)) DBUG_RETURN(true); } for (item_pos= 0, sl= first_sl ; item_pos < count; sl= sl->next_select(), item_pos++) { Item *item_tmp; List_iterator_fast itx(sl->item_list); for (uint holder_pos= 0 ; (item_tmp= itx++); holder_pos++) { /* If the outer query has a GROUP BY clause, an outer reference to this query block may have been wrapped in a Item_outer_ref, which has not been fixed yet. An Item_type_holder must be created based on a fixed Item, so use the inner Item instead. */ DBUG_ASSERT(item_tmp->fixed() || (item_tmp->type() == Item::REF_ITEM && ((Item_ref *)(item_tmp))->ref_type() == Item_ref::OUTER_REF)); if (!item_tmp->fixed()) item_tmp= item_tmp->real_item(); holders[holder_pos].add_argument(item_tmp); } } for (uint pos= 0; pos < first_sl->item_list.elements; pos++) { if (holders[pos].aggregate_attributes(thd_arg)) DBUG_RETURN(true); } DBUG_RETURN(false); } /** Join data types for the leftmost "count" UNION parts and store corresponding Item_type_holder's into "types". */ bool st_select_lex_unit::join_union_item_types(THD *thd_arg, List &types, uint count) { DBUG_ENTER("st_select_lex_unit::join_union_select_list_types"); SELECT_LEX *first_sl= first_select(); Type_holder *holders; if (!(holders= new (thd_arg->mem_root) Type_holder[first_sl->item_list.elements]) || join_union_type_handlers(thd_arg, holders, count) || join_union_type_attributes(thd_arg, holders, count)) DBUG_RETURN(true); bool is_recursive= with_element && with_element->is_recursive; types.empty(); List_iterator_fast it(first_sl->item_list); Item *item_tmp; for (uint pos= 0; (item_tmp= it++); pos++) { /* SQL standard requires forced nullability only for recursive columns. However type aggregation in our implementation so far does not differentiate between recursive and non-recursive columns of a recursive CTE. TODO: this should be fixed. */ bool pos_maybe_null= is_recursive ? true : holders[pos].get_maybe_null(); /* Error's in 'new' will be detected after loop */ types.push_back(new (thd_arg->mem_root) Item_type_holder(thd_arg, item_tmp, holders[pos].type_handler(), &holders[pos]/*Type_all_attributes*/, pos_maybe_null)); } if (unlikely(thd_arg->is_fatal_error)) DBUG_RETURN(true); // out of memory DBUG_RETURN(false); } bool init_item_int(THD* thd, Item_int* &item) { if (!item) { Query_arena *arena, backup_arena; arena= thd->activate_stmt_arena_if_needed(&backup_arena); item= new (thd->mem_root) Item_int(thd, 0); if (arena) thd->restore_active_arena(arena, &backup_arena); if (!item) return false; } else { item->value= 0; } return true; } bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg, select_result *sel_result, ulonglong additional_options) { SELECT_LEX *lex_select_save= thd->lex->current_select; SELECT_LEX *sl, *first_sl= first_select(); bool is_recursive= with_element && with_element->is_recursive; bool is_rec_result_table_created= false; uint union_part_count= 0; select_result *tmp_result; bool is_union_select; bool have_except= false, have_intersect= false, have_except_all_or_intersect_all= false; bool instantiate_tmp_table= false; bool single_tvc= !first_sl->next_select() && first_sl->tvc; bool single_tvc_wo_order= single_tvc && !first_sl->order_list.elements; DBUG_ENTER("st_select_lex_unit::prepare"); DBUG_ASSERT(thd == current_thd); if (is_recursive && (sl= first_sl->next_select())) { SELECT_LEX *next_sl; for ( ; ; sl= next_sl) { next_sl= sl->next_select(); if (!next_sl) break; if (next_sl->with_all_modifier != sl->with_all_modifier) { my_error(ER_NOT_SUPPORTED_YET, MYF(0), "mix of ALL and DISTINCT UNION operations in recursive CTE spec"); DBUG_RETURN(TRUE); } } } describe= additional_options & SELECT_DESCRIBE; /* Save fake_select_lex in case we don't need it for anything but global parameters. */ if (saved_fake_select_lex == NULL) // Don't overwrite on PS second prepare saved_fake_select_lex= fake_select_lex; /* result object should be reassigned even if preparing already done for max/min subquery (ALL/ANY optimization) */ result= sel_result; if (prepared) { if (describe) { /* fast reinit for EXPLAIN */ for (sl= first_sl; sl; sl= sl->next_select()) { if (sl->tvc) { sl->tvc->result= result; if (result->prepare(sl->item_list, this)) DBUG_RETURN(TRUE); sl->tvc->select_options|= SELECT_DESCRIBE; } else { sl->join->result= result; lim.clear(); if (!sl->join->procedure && result->prepare(sl->join->fields_list, this)) { DBUG_RETURN(TRUE); } sl->join->select_options|= SELECT_DESCRIBE; sl->join->reinit(); } } } DBUG_RETURN(FALSE); } prepared= 1; saved_error= FALSE; thd->lex->current_select= sl= first_sl; found_rows_for_union= first_sl->options & OPTION_FOUND_ROWS; is_union_select= is_unit_op() || fake_select_lex || single_tvc; /* If we are reading UNION output and the UNION is in the IN/ANY/ALL/EXISTS subquery, then ORDER BY is redundant and hence should be removed. Example: select ... col IN (select col2 FROM t1 union select col3 from t2 ORDER BY 1) (as for ORDER BY ... LIMIT, it currently not supported inside IN/ALL/ANY subqueries) (For non-UNION this removal of ORDER BY clause is done in check_and_do_in_subquery_rewrites()) */ if (item && is_unit_op() && (item->is_in_predicate() || item->is_exists_predicate())) { global_parameters()->order_list.first= NULL; global_parameters()->order_list.elements= 0; } /* will only optimize once */ if (!bag_set_op_optimized && !is_recursive) { optimize_bag_operation(false); } for (SELECT_LEX *s= first_sl; s; s= s->next_select()) { switch (s->linkage) { case INTERSECT_TYPE: have_intersect= TRUE; if (!s->distinct){ have_except_all_or_intersect_all= true; } break; case EXCEPT_TYPE: have_except= TRUE; if (!s->distinct){ have_except_all_or_intersect_all= TRUE; } break; default: break; } } /* Global option */ if (is_union_select || is_recursive) { if ((single_tvc_wo_order && !fake_select_lex) || (is_unit_op() && !union_needs_tmp_table() && !have_except && !have_intersect && !single_tvc)) { SELECT_LEX *last= first_select(); while (last->next_select()) last= last->next_select(); if (!(tmp_result= union_result= new (thd->mem_root) select_union_direct(thd, sel_result, last))) goto err; /* purecov: inspected */ fake_select_lex= NULL; instantiate_tmp_table= false; } else { if (!is_recursive) { /* class "select_unit_ext" handles query contains EXCEPT ALL and / or INTERSECT ALL. Others are handled by class "select_unit" If have EXCEPT ALL or INTERSECT ALL in the query. First operand should be UNION ALL */ if (have_except_all_or_intersect_all) { union_result= new (thd->mem_root) select_unit_ext(thd); first_sl->distinct= false; } else union_result= new (thd->mem_root) select_unit(thd); } else { with_element->rec_result= new (thd->mem_root) select_union_recursive(thd); union_result= with_element->rec_result; if (fake_select_lex) { if (fake_select_lex->order_list.first || fake_select_lex->limit_params.explicit_limit) { my_error(ER_NOT_SUPPORTED_YET, MYF(0), "global ORDER_BY/LIMIT in recursive CTE spec"); goto err; } fake_select_lex->cleanup(); fake_select_lex= NULL; } } if (!(tmp_result= union_result)) goto err; /* purecov: inspected */ instantiate_tmp_table= true; } } else tmp_result= sel_result; sl->context.resolve_in_select_list= TRUE; if (!is_union_select && !is_recursive) { if (sl->tvc) { if (sl->tvc->prepare(thd, sl, tmp_result, this)) goto err; } else { if (prepare_join(thd, first_sl, tmp_result, additional_options, is_union_select)) goto err; if (derived_arg && derived_arg->table && derived_arg->derived_type == VIEW_ALGORITHM_MERGE && derived_arg->table->versioned()) { /* Got versioning conditions (see vers_setup_conds()), need to update derived_arg. */ derived_arg->where= first_sl->where; } } types= first_sl->item_list; goto cont; } if (sl->tvc && sl->order_list.elements && !sl->tvc->to_be_wrapped_as_with_tail()) { SELECT_LEX_UNIT *unit= sl->master_unit(); if (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW) { unit->fake_select_lex= 0; unit->saved_fake_select_lex= 0; } else { if (!unit->first_select()->next_select()) { if (!unit->fake_select_lex) { Query_arena *arena, backup_arena; arena= thd->activate_stmt_arena_if_needed(&backup_arena); bool rc= unit->add_fake_select_lex(thd); if (arena) thd->restore_active_arena(arena, &backup_arena); if (rc) goto err; } SELECT_LEX *fake= unit->fake_select_lex; fake->order_list= sl->order_list; fake->limit_params= sl->limit_params; sl->order_list.empty(); sl->limit_params.clear(); if (describe) fake->options|= SELECT_DESCRIBE; } else if (!sl->limit_params.explicit_limit) sl->order_list.empty(); } } for (;sl; sl= sl->next_select(), union_part_count++) { if (sl->tvc) { if (sl->tvc->to_be_wrapped_as_with_tail() && !(thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)) { st_select_lex *wrapper_sl= wrap_tvc_with_tail(thd, sl); if (!wrapper_sl) goto err; if (sl == first_sl) first_sl= wrapper_sl; sl= wrapper_sl; if (prepare_join(thd, sl, tmp_result, additional_options, is_union_select)) goto err; } else if (sl->tvc->prepare(thd, sl, tmp_result, this)) goto err; } else if (prepare_join(thd, sl, tmp_result, additional_options, is_union_select)) goto err; /* setup_tables_done_option should be set only for very first SELECT, because it protect from secont setup_tables call for select-like non select commands (DELETE/INSERT/...) and they use only very first SELECT (for union it can be only INSERT ... SELECT). */ additional_options&= ~OPTION_SETUP_TABLES_DONE; /* Use items list of underlaid select for derived tables to preserve information about fields lengths and exact types */ if (sl == first_sl) { if (with_element) { if (with_element->process_columns_of_derived_unit(thd, this)) goto err; if (check_duplicate_names(thd, sl->item_list, 0)) goto err; } } else { if (first_sl->item_list.elements != sl->item_list.elements) { my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT, ER_THD(thd, ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT), MYF(0)); goto err; } } if (is_recursive) { if (!with_element->is_anchor(sl)) sl->uncacheable|= UNCACHEABLE_UNITED; if (!is_rec_result_table_created && (!sl->next_select() || sl->next_select() == with_element->first_recursive)) { ulonglong create_options; create_options= (first_sl->options | thd->variables.option_bits | TMP_TABLE_ALL_COLUMNS); // Join data types for all non-recursive parts of a recursive UNION if (join_union_item_types(thd, types, union_part_count + 1)) goto err; if (union_result->create_result_table(thd, &types, MY_TEST(union_distinct), create_options, &derived_arg->alias, false, instantiate_tmp_table, false, 0)) goto err; if (have_except_all_or_intersect_all) { union_result->init(); } if (!derived_arg->table) { bool res= false; if ((!derived_arg->is_with_table_recursive_reference() || !derived_arg->derived_result) && !(derived_arg->derived_result= new (thd->mem_root) select_unit(thd))) goto err; // out of memory thd->create_tmp_table_for_derived= TRUE; res= derived_arg->derived_result->create_result_table(thd, &types, FALSE, create_options, &derived_arg->alias, FALSE, FALSE, FALSE, 0); thd->create_tmp_table_for_derived= FALSE; if (res) goto err; derived_arg->derived_result->set_unit(this); derived_arg->table= derived_arg->derived_result->table; if (derived_arg->is_with_table_recursive_reference()) { /* Here 'derived_arg' is the primary recursive table reference */ derived_arg->with->rec_result-> rec_table_refs.push_back(derived_arg); } } with_element->mark_as_with_prepared_anchor(); is_rec_result_table_created= true; } } } // In case of a non-recursive UNION, join data types for all UNION parts. if (!is_recursive && join_union_item_types(thd, types, union_part_count)) goto err; cont: /* If the query is using select_union_direct, we have postponed preparation of the underlying select_result until column types are known. */ if (union_result != NULL && union_result->postponed_prepare(types)) DBUG_RETURN(true); if (is_union_select) { /* Check that it was possible to aggregate all collations together for UNION. */ List_iterator_fast tp(types); Item *type; ulonglong create_options; uint save_tablenr= 0; table_map save_map= 0; uint save_maybe_null= 0; while ((type= tp++)) { /* Test if the aggregated data type is OK for a UNION element. E.g. in case of string data, DERIVATION_NONE is not allowed. */ if (type->type_handler()->union_element_finalize(type)) goto err; } /* Disable the usage of fulltext searches in the last union branch. This is a temporary 5.x limitation because of the way the fulltext search functions are handled by the optimizer. This is manifestation of the more general problems of "taking away" parts of a SELECT statement post-fix_fields(). This is generally not doable since various flags are collected in various places (e.g. SELECT_LEX) that carry information about the presence of certain expressions or constructs in the parts of the query. When part of the query is taken away it's not clear how to "divide" the meaning of these accumulated flags and what to carry over to the recipient query (SELECT_LEX). */ if (global_parameters()->ftfunc_list->elements && global_parameters()->order_list.elements && global_parameters() != fake_select_lex) { ORDER *ord; Item_func::Functype ft= Item_func::FT_FUNC; for (ord= global_parameters()->order_list.first; ord; ord= ord->next) if ((*ord->item)->walk (&Item::find_function_processor, FALSE, &ft)) { my_error (ER_CANT_USE_OPTION_HERE, MYF(0), "MATCH()"); goto err; } } create_options= (first_sl->options | thd->variables.option_bits | TMP_TABLE_ALL_COLUMNS); /* Force the temporary table to be a MyISAM table if we're going to use fullext functions (MATCH ... AGAINST .. IN BOOLEAN MODE) when reading from it (this should be removed in 5.2 when fulltext search is moved out of MyISAM). */ if (global_parameters()->ftfunc_list->elements) create_options= create_options | TMP_TABLE_FORCE_MYISAM; /* extra field counter */ uint hidden= 0; Item_int *addon_fields[2]= {0}; if (!is_recursive) { if (have_except_all_or_intersect_all) { /* add duplicate_count */ ++hidden; } /* add intersect_count */ if (have_intersect) ++hidden; for(uint i= 0; i< hidden; i++) { init_item_int(thd, addon_fields[i]); types.push_front(addon_fields[i]); addon_fields[i]->name.str= i ? "__CNT_1" : "__CNT_2"; addon_fields[i]->name.length= 7; } bool error= union_result->create_result_table(thd, &types, MY_TEST(union_distinct) || have_except_all_or_intersect_all || have_intersect, create_options, &empty_clex_str, false, instantiate_tmp_table, false, hidden); union_result->addon_cnt= hidden; for (uint i= 0; i < hidden; i++) types.pop(); if (unlikely(error)) 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; save_maybe_null= result_table_list.maybe_null_exec; } bzero((char*) &result_table_list, sizeof(result_table_list)); result_table_list.db.str= (char*) ""; result_table_list.db.length= 0; result_table_list.table_name.str= result_table_list.alias.str= "union"; result_table_list.table_name.length= result_table_list.alias.length= sizeof("union")-1; 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; result_table_list.maybe_null_exec= save_maybe_null; } thd->lex->current_select= lex_select_save; if (!item_list.elements) { Query_arena *arena, backup_arena; arena= thd->activate_stmt_arena_if_needed(&backup_arena); saved_error= table->fill_item_list(&item_list); for (uint i= 0; i < hidden; i++) item_list.pop(); if (arena) thd->restore_active_arena(arena, &backup_arena); if (unlikely(saved_error)) goto err; if (fake_select_lex != NULL && (thd->stmt_arena->is_stmt_prepare() || (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW))) { /* Validate the global parameters of this union */ init_prepare_fake_select_lex(thd, TRUE); /* 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->variables.option_bits, result))) { fake_select_lex->table_list.empty(); DBUG_RETURN(TRUE); } /* Fake st_select_lex should have item list for correct ref_array allocation. */ fake_select_lex->item_list= item_list; thd->lex->current_select= fake_select_lex; /* We need to add up n_sum_items in order to make the correct allocation in setup_ref_array(). */ fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items; } } else { /* We're in execution of a prepared statement or stored procedure: reset field items to point at fields from the created temporary table. */ table->reset_item_list(&item_list, hidden); } if (fake_select_lex != NULL && (thd->stmt_arena->is_stmt_prepare() || (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW))) { if (!fake_select_lex->join && !(fake_select_lex->join= new JOIN(thd, item_list, thd->variables.option_bits, result))) { fake_select_lex->table_list.empty(); DBUG_RETURN(TRUE); } saved_error= fake_select_lex->join-> prepare(fake_select_lex->table_list.first, 0, global_parameters()->order_list.elements, // og_num global_parameters()->order_list.first, // order false, NULL, NULL, NULL, fake_select_lex, this); fake_select_lex->table_list.empty(); } } thd->lex->current_select= lex_select_save; DBUG_RETURN(saved_error || thd->is_fatal_error); err: thd->lex->current_select= lex_select_save; (void) cleanup(); DBUG_RETURN(TRUE); } /** @brief Optimize a sequence of set operations @param first_sl first select of the level now under processing @details The method optimizes with the following rules: - (1)If a subsequence of INTERSECT contains at least one INTERSECT DISTINCT or this subsequence is followed by UNION/EXCEPT DISTINCT then all elements in the subsequence can changed for INTERSECT DISTINCT - (2)If previous set operation is DISTINCT then EXCEPT ALL can be replaced for EXCEPT DISTINCT - (3)If UNION DISTINCT / EXCEPT DISTINCT follows a subsequence of UNION ALL then all set operations of this subsequence can be replaced for UNION DISTINCT For derived table it will look up outer select, and do optimize based on outer select. Variable "union_distinct" will be updated in the end. Not compatible with Oracle Mode. */ void st_select_lex_unit::optimize_bag_operation(bool is_outer_distinct) { /* skip run optimize for: ORACLE MODE CREATE VIEW PREPARE ... FROM recursive */ if ((thd->variables.sql_mode & MODE_ORACLE) || (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW) || (fake_select_lex != NULL && thd->stmt_arena->is_stmt_prepare()) || (with_element && with_element->is_recursive )) return; DBUG_ASSERT(!bag_set_op_optimized); SELECT_LEX *sl; /* INTERSECT subsequence can occur only at the very beginning */ /* The first select with linkage == INTERSECT_TYPE */ SELECT_LEX *intersect_start= NULL; /* The first select after the INTERSECT subsequence */ SELECT_LEX *intersect_end= NULL; /* Will point to the last node before UNION ALL subsequence. Index can be disable there. */ SELECT_LEX *disable_index= NULL; /* True if there is a select with: linkage == INTERSECT_TYPE && distinct==true */ bool any_intersect_distinct= false; SELECT_LEX *prev_sl= first_select(); /* process INTERSECT subsequence in the begining */ for (sl= prev_sl->next_select(); sl; prev_sl= sl, sl= sl->next_select()) { if (sl->linkage != INTERSECT_TYPE) { intersect_end= sl; break; } else { if (!intersect_start) intersect_start= sl; if (sl->distinct) { any_intersect_distinct= true; disable_index= sl; } } } /* if subquery only contains INTERSECT and outer is UNION DISTINCT*/ if (!sl && is_outer_distinct) any_intersect_distinct= true; /* The first select of the current UNION ALL subsequence */ SELECT_LEX *union_all_start= NULL; for ( ; sl; prev_sl= sl, sl= sl->next_select()) { DBUG_ASSERT (sl->linkage != INTERSECT_TYPE); if (!sl->distinct) { if (sl->linkage == UNION_TYPE) { if (!union_all_start) { union_all_start= sl; } } else { DBUG_ASSERT (sl->linkage == EXCEPT_TYPE); union_all_start= NULL; if (prev_sl->distinct && prev_sl->is_set_op()) { sl->distinct= true; disable_index= sl; } } } else { /* sl->distinct == true */ for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select()) { si->distinct= true; } union_all_start= NULL; disable_index= sl; } } if (is_outer_distinct) { for (SELECT_LEX *si= union_all_start; si && si != sl; si= si->next_select()) { si->distinct= true; } union_all_start= NULL; } if (any_intersect_distinct || (intersect_end != NULL && intersect_end->distinct)) { for (sl= intersect_start; sl && sl != intersect_end; sl= sl->next_select()) { sl->distinct= true; if (disable_index && disable_index->linkage == INTERSECT_TYPE) disable_index= sl; } } /* if disable_index points to a INTERSECT, based on rule 1 we can set it to the last INTERSECT node. */ if (disable_index && disable_index->linkage == INTERSECT_TYPE && intersect_end && intersect_end->distinct) disable_index= intersect_end; /* union_distinct controls when to disable index */ union_distinct= disable_index; /* recursive call this function for whole lex tree */ for(sl= first_select(); sl; sl= sl->next_select()) { if (sl->is_unit_nest() && sl->first_inner_unit() && !sl->first_inner_unit()->bag_set_op_optimized) sl->first_inner_unit()->optimize_bag_operation(sl->distinct); } /* mark as optimized */ bag_set_op_optimized= true; } /** 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(); DBUG_ENTER("st_select_lex_unit::optimize"); if (optimized && !uncacheable && !describe) DBUG_RETURN(false); if (with_element && with_element->is_recursive && optimize_started) DBUG_RETURN(false); optimize_started= true; if (uncacheable || !item || !item->assigned() || describe) { if (item) item->reset_value_registration(); if (optimized && item) { if (item->assigned()) { item->assigned(0); // We will reinit & rexecute unit item->reset(); } if (table->is_created()) { table->file->ha_delete_all_rows(); table->file->info(HA_STATUS_VARIABLE); } /* re-enabling indexes for next subselect iteration */ if ((union_result->force_enable_index_if_needed() || union_distinct)) { if(table->file->ha_enable_indexes(HA_KEY_SWITCH_ALL)) DBUG_ASSERT(0); else table->no_keyread= 0; } } for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select()) { if (sl->tvc) { sl->tvc->select_options= (lim.is_unlimited() || sl->braces) ? sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; if (sl->tvc->optimize(thd)) { thd->lex->current_select= lex_select_save; DBUG_RETURN(TRUE); } if (derived) sl->increase_derived_records(sl->tvc->get_records()); continue; } thd->lex->current_select= sl; if (optimized) saved_error= sl->join->reinit(); else { set_limit(sl); if (sl == global_parameters() || describe) { lim.remove_offset(); /* We can't use LIMIT at this stage if we are using ORDER BY for the whole query */ if (sl->order_list.first || describe) lim.set_unlimited(); } /* 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= (lim.is_unlimited() || sl->braces) ? sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; saved_error= sl->join->optimize(); } if (unlikely(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; bool first_execution= !executed; DBUG_ENTER("st_select_lex_unit::exec"); bool was_executed= executed; if (executed && !uncacheable && !describe) DBUG_RETURN(FALSE); executed= 1; if (!(uncacheable & ~UNCACHEABLE_EXPLAIN) && item && !item->with_recursive_reference) item->make_const(); saved_error= optimize(); create_explain_query_if_not_exists(thd->lex, thd->mem_root); if (!saved_error && !was_executed) save_union_explain(thd->lex->explain); if (unlikely(saved_error)) DBUG_RETURN(saved_error); if (union_result) { union_result->init(); if (uncacheable & UNCACHEABLE_DEPENDENT && union_result->table && union_result->table->is_created()) { union_result->table->file->ha_delete_all_rows(); union_result->table->file->ha_enable_indexes(HA_KEY_SWITCH_ALL); } } if (uncacheable || !item || !item->assigned() || describe) { if (!fake_select_lex && !(with_element && with_element->is_recursive)) union_result->cleanup(); for (SELECT_LEX *sl= select_cursor; sl; sl= sl->next_select()) { ha_rows records_at_start= 0; thd->lex->current_select= sl; if (union_result) union_result->change_select(); if (fake_select_lex) { if (sl != thd->lex->first_select_lex()) fake_select_lex->uncacheable|= sl->uncacheable; else fake_select_lex->uncacheable= 0; } { set_limit(sl); if (sl == global_parameters() || describe) { lim.remove_offset(); /* We can't use LIMIT at this stage if we are using ORDER BY for the whole query */ if (sl->order_list.first || describe) lim.set_unlimited(); } /* 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. */ if (sl->tvc) { sl->tvc->select_options= (lim.is_unlimited() || sl->braces) ? sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; saved_error= sl->tvc->optimize(thd); } else { sl->join->select_options= (lim.is_unlimited() || sl->braces) ? sl->options & ~OPTION_FOUND_ROWS : sl->options | found_rows_for_union; saved_error= sl->join->optimize(); } } if (likely(!saved_error)) { records_at_start= table->file->stats.records; if (sl->tvc) sl->tvc->exec(sl); else sl->join->exec(); if (sl == union_distinct && !have_except_all_or_intersect_all && !(with_element && with_element->is_recursive)) { // This is UNION DISTINCT, so there should be a fake_select_lex DBUG_ASSERT(fake_select_lex != NULL); if (unlikely(table->file->ha_disable_indexes(HA_KEY_SWITCH_ALL))) DBUG_RETURN(TRUE); table->no_keyread=1; } if (!sl->tvc) saved_error= sl->join->error; if (likely(!saved_error)) { examined_rows+= thd->get_examined_row_count(); thd->set_examined_row_count(0); if (union_result->flush()) { thd->lex->current_select= lex_select_save; DBUG_RETURN(1); } } } if (unlikely(saved_error)) { thd->lex->current_select= lex_select_save; DBUG_RETURN(saved_error); } if (fake_select_lex != NULL) { /* Needed for the following test and for records_at_start in next loop */ int error= table->file->info(HA_STATUS_VARIABLE); if (unlikely(error)) { table->file->print_error(error, MYF(0)); DBUG_RETURN(1); } } if (found_rows_for_union && !sl->braces && !lim.is_unlimited()) { /* This is a union without braces. Remember the number of rows that could also have been part of the result set. We get this from the difference of between total number of possible rows and actual rows added to the temporary table. */ add_rows+= (ulonglong) (thd->limit_found_rows - (ulonglong) ((table->file->stats.records - records_at_start))); } if (thd->killed == ABORT_QUERY) { /* Stop execution of the remaining queries in the UNIONS, and produce the current result. */ push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN, ER_QUERY_EXCEEDED_ROWS_EXAMINED_LIMIT, ER_THD(thd, ER_QUERY_EXCEEDED_ROWS_EXAMINED_LIMIT), thd->accessed_rows_and_keys, thd->lex->limit_rows_examined->val_uint()); thd->reset_killed(); break; } } } DBUG_EXECUTE_IF("show_explain_probe_union_read", dbug_serve_apcs(thd, 1);); { List empty_list; empty_list.empty(); /* Disable LIMIT ROWS EXAMINED in order to produce the possibly incomplete result of the UNION without interruption due to exceeding the limit. */ thd->lex->limit_rows_examined_cnt= ULONGLONG_MAX; // Check if EOM if (fake_select_lex != NULL && likely(!thd->is_fatal_error)) { /* Send result to 'result' */ saved_error= true; set_limit(global_parameters()); init_prepare_fake_select_lex(thd, first_execution); JOIN *join= fake_select_lex->join; saved_error= false; if (!join) { /* allocate JOIN for fake select only once (prevent mysql_select automatic allocation) TODO: The above is nonsense. mysql_select() will not allocate the join if one already exists. There must be some other reason why we don't let it allocate the join. Perhaps this is because we need some special parameter values passed to join constructor? */ if (unlikely(!(fake_select_lex->join= new JOIN(thd, item_list, fake_select_lex->options, result)))) { fake_select_lex->table_list.empty(); goto err; } fake_select_lex->join->no_const_tables= TRUE; /* Fake st_select_lex should have item list for correct ref_array allocation. */ fake_select_lex->item_list= item_list; /* We need to add up n_sum_items in order to make the correct allocation in setup_ref_array(). Don't add more sum_items if we have already done JOIN::prepare for this (with a different join object) */ if (fake_select_lex->ref_pointer_array.is_null()) fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items; if (!was_executed) save_union_explain_part2(thd->lex->explain); saved_error= mysql_select(thd, &result_table_list, item_list, NULL, global_parameters()->order_list.elements, global_parameters()->order_list.first, NULL, NULL, NULL, fake_select_lex->options | SELECT_NO_UNLOCK, result, this, fake_select_lex); } else { if (describe) { /* In EXPLAIN command, constant subqueries that do not use any tables are executed two times: - 1st time is a real evaluation to get the subquery value - 2nd time is to produce EXPLAIN output rows. 1st execution sets certain members (e.g. select_result) to perform subquery execution rather than EXPLAIN line production. In order to reset them back, we re-do all of the actions (yes it is ugly): */ // psergey-todo: is the above really necessary anymore?? join->init(thd, item_list, fake_select_lex->options, result); saved_error= mysql_select(thd, &result_table_list, item_list, NULL, global_parameters()->order_list.elements, global_parameters()->order_list.first, NULL, NULL, NULL, fake_select_lex->options | SELECT_NO_UNLOCK, result, this, fake_select_lex); } else { join->join_examined_rows= 0; saved_error= join->reinit(); join->exec(); } } fake_select_lex->table_list.empty(); if (likely(!saved_error)) { thd->limit_found_rows = (ulonglong)table->file->stats.records + add_rows; thd->inc_examined_row_count(examined_rows); } /* Mark for slow query log if any of the union parts didn't use indexes efficiently */ } } thd->lex->current_select= lex_select_save; err: thd->lex->set_limit_rows_examined(); DBUG_RETURN(saved_error); } /** @brief Execute the union of the specification of a recursive with table @details The method is performed only for the units that are specifications if recursive with table T. If the specification contains an anchor part then the first call of this method executes only this part while the following calls execute the recursive part. If there are no anchors each call executes the whole unit. Before the excution the method cleans up the temporary table to where the new rows of the recursive table are sent. After the execution the unit these rows are copied to the temporary tables created for recursive references of T. If the specification if T is restricted (standards compliant) then these temporary tables are cleaned up before new rows are copied into them. @retval false on success true on failure */ bool st_select_lex_unit::exec_recursive() { st_select_lex *lex_select_save= thd->lex->current_select; st_select_lex *start= with_element->first_recursive; TABLE *incr_table= with_element->rec_result->incr_table; st_select_lex *end= NULL; bool is_unrestricted= with_element->is_unrestricted(); List_iterator_fast li(with_element->rec_result->rec_table_refs); TMP_TABLE_PARAM *tmp_table_param= &with_element->rec_result->tmp_table_param; ha_rows examined_rows= 0; bool was_executed= executed; TABLE_LIST *rec_tbl; DBUG_ENTER("st_select_lex_unit::exec_recursive"); executed= 1; create_explain_query_if_not_exists(thd->lex, thd->mem_root); if (!was_executed) save_union_explain(thd->lex->explain); if (with_element->level == 0) { if (!incr_table->is_created() && instantiate_tmp_table(incr_table, tmp_table_param->keyinfo, tmp_table_param->start_recinfo, &tmp_table_param->recinfo, 0)) DBUG_RETURN(1); incr_table->file->extra(HA_EXTRA_WRITE_CACHE); incr_table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); start= first_select(); if (with_element->with_anchor) end= with_element->first_recursive; } else if (unlikely((saved_error= incr_table->file->ha_delete_all_rows()))) goto err; for (st_select_lex *sl= start ; sl != end; sl= sl->next_select()) { if (with_element->level) { for (TABLE_LIST *derived= with_element->derived_with_rec_ref.first; derived; derived= derived->next_with_rec_ref) { if (derived->is_materialized_derived()) { if (derived->table->is_created()) derived->table->file->ha_delete_all_rows(); derived->table->reginfo.join_tab->preread_init_done= false; } } } thd->lex->current_select= sl; set_limit(sl); if (sl->tvc) sl->tvc->exec(sl); else { sl->join->exec(); saved_error= sl->join->error; } if (likely(!saved_error)) { examined_rows+= thd->get_examined_row_count(); thd->set_examined_row_count(0); if (unlikely(union_result->flush())) { thd->lex->current_select= lex_select_save; DBUG_RETURN(1); } } if (unlikely(saved_error)) { thd->lex->current_select= lex_select_save; goto err; } } thd->inc_examined_row_count(examined_rows); incr_table->file->info(HA_STATUS_VARIABLE); if (with_element->level && incr_table->file->stats.records == 0) with_element->set_as_stabilized(); else with_element->level++; while ((rec_tbl= li++)) { TABLE *rec_table= rec_tbl->table; saved_error= incr_table->insert_all_rows_into_tmp_table(thd, rec_table, tmp_table_param, !is_unrestricted); if (!with_element->rec_result->first_rec_table_to_update) with_element->rec_result->first_rec_table_to_update= rec_table; if (with_element->level == 1 && rec_table->reginfo.join_tab) rec_table->reginfo.join_tab->preread_init_done= true; } for (Item_subselect *sq= with_element->sq_with_rec_ref.first; sq; sq= sq->next_with_rec_ref) { sq->reset(); sq->engine->force_reexecution(); } thd->lex->current_select= lex_select_save; err: thd->lex->set_limit_rows_examined(); DBUG_RETURN(saved_error); } bool st_select_lex_unit::cleanup() { bool error= 0; DBUG_ENTER("st_select_lex_unit::cleanup"); if (cleaned) { DBUG_RETURN(FALSE); } if (with_element && with_element->is_recursive && union_result) { select_union_recursive *result= with_element->rec_result; if (++result->cleanup_count == with_element->rec_outer_references) { /* Perform cleanup for with_element and for all with elements mutually recursive with it. */ cleaned= 1; with_element->get_next_mutually_recursive()->spec->cleanup(); } else { /* Just increment by 1 cleanup_count for with_element and for all with elements mutually recursive with it. */ With_element *with_elem= with_element; while ((with_elem= with_elem->get_next_mutually_recursive()) != with_element) with_elem->rec_result->cleanup_count++; DBUG_RETURN(FALSE); } } columns_are_renamed= false; cleaned= 1; for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) error|= sl->cleanup(); if (fake_select_lex) { error|= fake_select_lex->cleanup(); /* There are two cases when we should clean order items: 1. UNION with SELECTs which all enclosed into braces in this case global_parameters == fake_select_lex 2. UNION where last SELECT is not enclosed into braces in this case global_parameters == 'last select' So we should use global_parameters->order_list for proper order list clean up. Note: global_parameters and fake_select_lex are always initialized for UNION */ DBUG_ASSERT(global_parameters()); if (global_parameters()->order_list.elements) { ORDER *ord; for (ord= global_parameters()->order_list.first; ord; ord= ord->next) (*ord->item)->walk (&Item::cleanup_processor, 0, 0); } } if (with_element && with_element->is_recursive) { if (union_result) { ((select_union_recursive *) union_result)->cleanup(); delete union_result; union_result= 0; } with_element->mark_as_cleaned(); } else { if (union_result) { delete union_result; union_result=0; // Safety if (table) free_tmp_table(thd, table); table= 0; // Safety } } DBUG_RETURN(error); } void st_select_lex_unit::reinit_exec_mechanism() { prepared= optimized= optimized_2= executed= 0; optimize_started= 0; if (with_element && with_element->is_recursive) with_element->reset_recursive_for_exec(); } /** Change the select_result object used to return the final result of the unit, replacing occurences of old_result with new_result. @param new_result New select_result object @param old_result Old select_result object @retval false Success @retval true Error */ bool st_select_lex_unit::change_result(select_result_interceptor *new_result, select_result_interceptor *old_result) { for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) { if (sl->join) if (sl->join->change_result(new_result, old_result)) return true; /* purecov: inspected */ } /* If there were a fake_select_lex->join, we would have to change the result of that also, but change_result() is called before such an object is created. */ DBUG_ASSERT(fake_select_lex == NULL || fake_select_lex->join == NULL); return false; } /* Get column type information for this unit. SYNOPSIS st_select_lex_unit::get_column_types() @param for_cursor if true return the list the fields retrieved by the cursor 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 *st_select_lex_unit::get_column_types(bool for_cursor) { SELECT_LEX *sl= first_select(); bool is_procedure= !sl->tvc && sl->join->procedure ; if (is_procedure) { /* Types for "SELECT * FROM t1 procedure analyse()" are generated during execute */ return &sl->join->procedure_fields_list; } if (is_unit_op()) { DBUG_ASSERT(prepared); /* Types are generated during prepare */ return &types; } return for_cursor ? sl->join->fields : &sl->item_list; } static void cleanup_order(ORDER *order) { for (; order; order= order->next) order->counter_used= 0; } bool st_select_lex::cleanup() { bool error= FALSE; DBUG_ENTER("st_select_lex::cleanup()"); DBUG_PRINT("info", ("select: %p (%u) JOIN %p", this, select_number, join)); cleanup_order(order_list.first); cleanup_order(group_list.first); cleanup_ftfuncs(this); if (join) { List_iterator ti(leaf_tables); TABLE_LIST *tbl; while ((tbl= ti++)) { if (tbl->is_recursive_with_table() && !tbl->is_with_table_recursive_reference()) { /* If query is killed before open_and_process_table() for tbl is called then 'with' is already set, but 'derived' is not. */ st_select_lex_unit *unit= tbl->with->spec; error|= (bool) error | (uint) unit->cleanup(); } } DBUG_ASSERT((st_select_lex*)join->select_lex == this); error= join->destroy(); delete join; join= 0; } leaf_tables.empty(); for (SELECT_LEX_UNIT *lex_unit= first_inner_unit(); lex_unit ; lex_unit= lex_unit->next_unit()) { if (lex_unit->with_element && lex_unit->with_element->is_recursive) continue; error= (bool) ((uint) error | (uint) lex_unit->cleanup()); } inner_refs_list.empty(); exclude_from_table_unique_test= FALSE; hidden_bit_fields= 0; DBUG_RETURN(error); } void st_select_lex::cleanup_all_joins(bool full) { SELECT_LEX_UNIT *unit; SELECT_LEX *sl; DBUG_ENTER("st_select_lex::cleanup_all_joins"); if (join) join->cleanup(full); for (unit= first_inner_unit(); unit; unit= unit->next_unit()) { if (unit->with_element && unit->with_element->is_recursive) continue; for (sl= unit->first_select(); sl; sl= sl->next_select()) sl->cleanup_all_joins(full); } DBUG_VOID_RETURN; } /** Set exclude_from_table_unique_test for selects of this unit and all underlying selects. @note used to exclude materialized derived tables (views) from unique table check. */ void st_select_lex_unit::set_unique_exclude() { for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) { sl->exclude_from_table_unique_test= TRUE; for (SELECT_LEX_UNIT *unit= sl->first_inner_unit(); unit; unit= unit->next_unit()) { unit->set_unique_exclude(); } } } /** @brief Check if the derived table is guaranteed to have distinct rows because of UNION operations used to populate it. @detail UNION operation removes duplicate rows from its output. That is, a query like select * from t1 UNION select * from t2 will not produce duplicate rows in its output, even if table t1 (and/or t2) contain duplicate rows. EXCEPT and INTERSECT operations also have this property. On the other hand, UNION ALL operation doesn't remove duplicates. (The SQL standard also defines EXCEPT ALL and INTERSECT ALL, but we don't support them). st_select_lex_unit computes its value left to right. That is, if there is a st_select_lex_unit object describing (select #1) OP1 (select #2) OP2 (select #3) then ((select #1) OP1 (select #2)) is computed first, and OP2 is computed second. How can one tell if st_select_lex_unit is guaranteed to have distinct output rows? This depends on whether the last operation was duplicate- removing or not: - UNION ALL is not duplicate-removing - all other operations are duplicate-removing */ bool st_select_lex_unit::check_distinct_in_union() { if (union_distinct && !union_distinct->next_select()) return true; return false; }