diff options
Diffstat (limited to 'sql/opt_subselect.cc')
| -rw-r--r-- | sql/opt_subselect.cc | 140 |
1 files changed, 99 insertions, 41 deletions
diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc index 0ad90e2ef3d..3d470b6ff5c 100644 --- a/sql/opt_subselect.cc +++ b/sql/opt_subselect.cc @@ -617,6 +617,18 @@ int check_and_do_in_subquery_rewrites(JOIN *join) thd->stmt_arena->state != Query_arena::PREPARED) */ { + SELECT_LEX *current= thd->lex->current_select; + thd->lex->current_select= current->return_after_parsing(); + char const *save_where= thd->where; + thd->where= "IN/ALL/ANY subquery"; + + bool failure= !in_subs->left_expr->fixed && + in_subs->left_expr->fix_fields(thd, &in_subs->left_expr); + thd->lex->current_select= current; + thd->where= save_where; + if (failure) + DBUG_RETURN(-1); /* purecov: deadcode */ + /* Check if the left and right expressions have the same # of columns, i.e. we don't have a case like @@ -630,18 +642,6 @@ int check_and_do_in_subquery_rewrites(JOIN *join) my_error(ER_OPERAND_COLUMNS, MYF(0), in_subs->left_expr->cols()); DBUG_RETURN(-1); } - - SELECT_LEX *current= thd->lex->current_select; - thd->lex->current_select= current->return_after_parsing(); - char const *save_where= thd->where; - thd->where= "IN/ALL/ANY subquery"; - - bool failure= !in_subs->left_expr->fixed && - in_subs->left_expr->fix_fields(thd, &in_subs->left_expr); - thd->lex->current_select= current; - thd->where= save_where; - if (failure) - DBUG_RETURN(-1); /* purecov: deadcode */ } DBUG_PRINT("info", ("Checking if subq can be converted to semi-join")); @@ -704,6 +704,12 @@ int check_and_do_in_subquery_rewrites(JOIN *join) if (!optimizer_flag(thd, OPTIMIZER_SWITCH_IN_TO_EXISTS) && !optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION)) my_error(ER_ILLEGAL_SUBQUERY_OPTIMIZER_SWITCHES, MYF(0)); + /* + Transform each subquery predicate according to its overloaded + transformer. + */ + if (subselect->select_transformer(join)) + DBUG_RETURN(-1); /* If the subquery predicate is IN/=ANY, analyse and set all possible @@ -755,12 +761,6 @@ int check_and_do_in_subquery_rewrites(JOIN *join) allany_subs->add_strategy(strategy); } - /* - Transform each subquery predicate according to its overloaded - transformer. - */ - if (subselect->select_transformer(join)) - DBUG_RETURN(-1); } } DBUG_RETURN(0); @@ -1593,8 +1593,19 @@ static bool convert_subq_to_sj(JOIN *parent_join, Item_in_subselect *subq_pred) if (subq_pred->left_expr->cols() == 1) { nested_join->sj_outer_expr_list.push_back(subq_pred->left_expr); + /* + Create Item_func_eq. Note that + 1. this is done on the statement, not execution, arena + 2. if it's a PS then this happens only once - on the first execution. + On following re-executions, the item will be fix_field-ed normally. + 3. Thus it should be created as if it was fix_field'ed, in particular + all pointers to items in the execution arena should be protected + with thd->change_item_tree + */ Item_func_eq *item_eq= - new Item_func_eq(subq_pred->left_expr, subq_lex->ref_pointer_array[0]); + new Item_func_eq(subq_pred->left_expr_orig, subq_lex->ref_pointer_array[0]); + if (subq_pred->left_expr_orig != subq_pred->left_expr) + thd->change_item_tree(item_eq->arguments(), subq_pred->left_expr); item_eq->in_equality_no= 0; sj_nest->sj_on_expr= and_items(sj_nest->sj_on_expr, item_eq); } @@ -4362,6 +4373,74 @@ int init_dups_weedout(JOIN *join, uint first_table, int first_fanout_table, uint /* + @brief + Set up semi-join Loose Scan strategy for execution + + @detail + Other strategies are done in setup_semijoin_dups_elimination(), + however, we need to set up Loose Scan earlier, before make_join_select is + called. This is to prevent make_join_select() from switching full index + scans into quick selects (which will break Loose Scan access). + + @return + 0 OK + 1 Error +*/ + +int setup_semijoin_loosescan(JOIN *join) +{ + uint i; + DBUG_ENTER("setup_semijoin_loosescan"); + + POSITION *pos= join->best_positions + join->const_tables; + for (i= join->const_tables ; i < join->top_join_tab_count; ) + { + JOIN_TAB *tab=join->join_tab + i; + switch (pos->sj_strategy) { + case SJ_OPT_MATERIALIZE: + case SJ_OPT_MATERIALIZE_SCAN: + i+= 1; /* join tabs are embedded in the nest */ + pos += pos->n_sj_tables; + break; + case SJ_OPT_LOOSE_SCAN: + { + /* We jump from the last table to the first one */ + tab->loosescan_match_tab= tab + pos->n_sj_tables - 1; + + /* LooseScan requires records to be produced in order */ + if (tab->select && tab->select->quick) + tab->select->quick->need_sorted_output(); + + for (uint j= i; j < i + pos->n_sj_tables; j++) + join->join_tab[j].inside_loosescan_range= TRUE; + + /* Calculate key length */ + uint keylen= 0; + uint keyno= pos->loosescan_picker.loosescan_key; + for (uint kp=0; kp < pos->loosescan_picker.loosescan_parts; kp++) + keylen += tab->table->key_info[keyno].key_part[kp].store_length; + + tab->loosescan_key= keyno; + tab->loosescan_key_len= keylen; + if (pos->n_sj_tables > 1) + tab[pos->n_sj_tables - 1].do_firstmatch= tab; + i+= pos->n_sj_tables; + pos+= pos->n_sj_tables; + break; + } + default: + { + i++; + pos++; + break; + } + } + } + DBUG_RETURN(FALSE); +} + + +/* Setup the strategies to eliminate semi-join duplicates. SYNOPSIS @@ -4469,8 +4548,6 @@ int setup_semijoin_dups_elimination(JOIN *join, ulonglong options, for (i= join->const_tables ; i < join->top_join_tab_count; ) { JOIN_TAB *tab=join->join_tab + i; - //POSITION *pos= join->best_positions + i; - uint keylen, keyno; switch (pos->sj_strategy) { case SJ_OPT_MATERIALIZE: case SJ_OPT_MATERIALIZE_SCAN: @@ -4480,26 +4557,7 @@ int setup_semijoin_dups_elimination(JOIN *join, ulonglong options, break; case SJ_OPT_LOOSE_SCAN: { - /* We jump from the last table to the first one */ - tab->loosescan_match_tab= tab + pos->n_sj_tables - 1; - - /* LooseScan requires records to be produced in order */ - if (tab->select && tab->select->quick) - tab->select->quick->need_sorted_output(); - - for (uint j= i; j < i + pos->n_sj_tables; j++) - join->join_tab[j].inside_loosescan_range= TRUE; - - /* Calculate key length */ - keylen= 0; - keyno= pos->loosescan_picker.loosescan_key; - for (uint kp=0; kp < pos->loosescan_picker.loosescan_parts; kp++) - keylen += tab->table->key_info[keyno].key_part[kp].store_length; - - tab->loosescan_key= keyno; - tab->loosescan_key_len= keylen; - if (pos->n_sj_tables > 1) - tab[pos->n_sj_tables - 1].do_firstmatch= tab; + /* Setup already handled by setup_semijoin_loosescan */ i+= pos->n_sj_tables; pos+= pos->n_sj_tables; break; |