diff options
Diffstat (limited to 'sql/item_subselect.h')
| -rw-r--r-- | sql/item_subselect.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/sql/item_subselect.h b/sql/item_subselect.h index 0e0f61aedd9..05c4528490f 100644 --- a/sql/item_subselect.h +++ b/sql/item_subselect.h @@ -159,8 +159,8 @@ public: null_value= 1; } /** - Set the subquery result to the default value for the predicate when the - subquery is known to produce an empty result. + Set the subquery result to a default value consistent with the semantics of + the result row produced for queries with implicit grouping. */ void no_rows_in_result()= 0; virtual bool select_transformer(JOIN *join); @@ -209,7 +209,7 @@ public: */ bool is_evaluated() const; bool is_uncacheable() const; - bool is_expensive() { return TRUE; } + bool is_expensive(); /* Used by max/min subquery to initialize value presence registration @@ -235,7 +235,7 @@ public: @retval TRUE if the predicate is expensive @retval FALSE otherwise */ - bool is_expensive_processor(uchar *arg) { return TRUE; } + bool is_expensive_processor(uchar *arg) { return is_expensive(); } /** Get the SELECT_LEX structure associated with this Item. @@ -581,6 +581,10 @@ public: bool fix_fields(THD *thd, Item **ref); void fix_length_and_dec(); void fix_after_pullout(st_select_lex *new_parent, Item **ref); + bool const_item() const + { + return Item_subselect::const_item() && left_expr->const_item(); + } void update_used_tables(); bool setup_mat_engine(); bool init_left_expr_cache(); |