diff options
Diffstat (limited to 'sql/item_cmpfunc.cc')
| -rw-r--r-- | sql/item_cmpfunc.cc | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc index 19e8385539f..3c871bc0663 100644 --- a/sql/item_cmpfunc.cc +++ b/sql/item_cmpfunc.cc @@ -5466,7 +5466,21 @@ void Item_equal::update_const() Item *item; while ((item= it++)) { - if (item->const_item()) + if (item->const_item() && + /* + Don't propagate constant status of outer-joined column. + Such a constant status here is a result of: + a) empty outer-joined table: in this case such a column has a + value of NULL; but at the same time other arguments of + Item_equal don't have to be NULLs and the value of the whole + multiple equivalence expression doesn't have to be NULL or FALSE + because of the outer join nature; + or + b) outer-joined table contains only 1 row: the result of + this column is equal to a row field value *or* NULL. + Both values are inacceptable as Item_equal constants. + */ + !item->is_outer_field()) { it.remove(); add(item); @@ -5505,7 +5519,8 @@ void Item_equal::update_used_tables() { item->update_used_tables(); used_tables_cache|= item->used_tables(); - const_item_cache&= item->const_item(); + /* see commentary at Item_equal::update_const() */ + const_item_cache&= item->const_item() && !item->is_outer_field(); } } |