diff options
Diffstat (limited to 'sql/sql_lex.cc')
| -rw-r--r-- | sql/sql_lex.cc | 91 |
1 files changed, 83 insertions, 8 deletions
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc index 0a4e112671e..e498b8b4a58 100644 --- a/sql/sql_lex.cc +++ b/sql/sql_lex.cc @@ -1735,17 +1735,29 @@ void st_select_lex_node::fast_exclude() } + +/* + Exclude a node from the tree lex structure, but leave it in the global + list of nodes. +*/ + +void st_select_lex_node::exclude_from_tree() +{ + if ((*prev= next)) + next->prev= prev; +} + + /* - excluding select_lex structure (except first (first select can't be + Exclude select_lex structure (except first (first select can't be deleted, because it is most upper select)) */ void st_select_lex_node::exclude() { - //exclude from global list + /* exclude from global list */ fast_exclude(); - //exclude from other structures - if ((*prev= next)) - next->prev= prev; + /* exclude from other structures */ + exclude_from_tree(); /* We do not need following statements, because prev pointer of first list element point to master->slave @@ -2145,8 +2157,8 @@ void st_select_lex::print_limit(THD *thd, select_limit == 1, and there should be no offset_limit. */ (((subs_type == Item_subselect::IN_SUBS) && - ((Item_in_subselect*)item)->exec_method == - Item_in_subselect::MATERIALIZATION) ? + ((Item_in_subselect*)item)->in_strategy & + SUBS_MATERIALIZATION) ? TRUE : (select_limit->val_int() == 1LL) && offset_limit == 0)); @@ -3076,6 +3088,70 @@ bool st_select_lex::add_index_hint (THD *thd, char *str, uint length) str, length)); } + +bool st_select_lex::optimize_unflattened_subqueries() +{ + for (SELECT_LEX_UNIT *un= first_inner_unit(); un; un= un->next_unit()) + { + Item_subselect *subquery_predicate= un->item; + if (subquery_predicate) + { + for (SELECT_LEX *sl= un->first_select(); sl; sl= sl->next_select()) + { + JOIN *inner_join= sl->join; + SELECT_LEX *save_select= un->thd->lex->current_select; + ulonglong save_options; + int res; + /* We need only 1 row to determine existence */ + un->set_limit(un->global_parameters); + un->thd->lex->current_select= sl; + save_options= inner_join->select_options; + if (un->outer_select()->options & SELECT_DESCRIBE) + { + /* Optimize the subquery in the context of EXPLAIN. */ + set_explain_type(); + inner_join->select_options= options; + } + res= inner_join->optimize(); + inner_join->select_options= save_options; + un->thd->lex->current_select= save_select; + if (res) + return TRUE; + } + } + } + return FALSE; +} + + +/** + Set the EXPLAIN type for this subquery. +*/ + +void st_select_lex::set_explain_type() +{ + SELECT_LEX *first= master_unit()->first_select(); + /* drop UNCACHEABLE_EXPLAIN, because it is for internal usage only */ + uint8 is_uncacheable= (uncacheable & ~UNCACHEABLE_EXPLAIN); + + type= ((&master_unit()->thd->lex->select_lex == this) ? + (first_inner_unit() || next_select() ? + "PRIMARY" : "SIMPLE") : + ((this == first) ? + ((linkage == DERIVED_TABLE_TYPE) ? + "DERIVED" : + ((is_uncacheable & UNCACHEABLE_DEPENDENT) ? + "DEPENDENT SUBQUERY" : + (is_uncacheable ? "UNCACHEABLE SUBQUERY" : + "SUBQUERY"))) : + ((is_uncacheable & UNCACHEABLE_DEPENDENT) ? + "DEPENDENT UNION": + is_uncacheable ? "UNCACHEABLE UNION": + "UNION"))); + options|= SELECT_DESCRIBE; +} + + /** A routine used by the parser to decide whether we are specifying a full partitioning or if only partitions to add or to split. @@ -3093,4 +3169,3 @@ bool st_lex::is_partition_management() const (alter_info.flags == ALTER_ADD_PARTITION || alter_info.flags == ALTER_REORGANIZE_PARTITION)); } - |