diff options
Diffstat (limited to 'sql/item.cc')
| -rw-r--r-- | sql/item.cc | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/sql/item.cc b/sql/item.cc index 71b73ae314f..34931af2c55 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -7507,7 +7507,8 @@ Item *Item::build_pushable_cond(THD *thd, col op const where op can be >/>=/</<=/=/<> Also the other cases are with [NOT] IN predicate, - [NOT] NULL predicate and LIKE predicate fall in the same category. + [NOT] NULL predicate and LIKE predicate fall + in the same category. The predicate should have only one non-constant argument and this argument will be a reference to a column that is used either as the first component of an index or statistics are available via @@ -7572,7 +7573,8 @@ Item *Item::build_pushable_cond(THD *thd, The implementation for this function use the 'walk' method to traverse the tree of this item with predicate_selectivity_checker() as the call-back parameter of the method. - + propagate_equal_fields() is called before this function is called so + Item_field::item_equal and Item_direct_view_ref::item_equal is set. @retval TRUE selectivity estimates are accurate @@ -7581,6 +7583,10 @@ Item *Item::build_pushable_cond(THD *thd, bool Item::with_accurate_selectivity_estimation() { + /* + For the below test one could use a virtual function but that would + take a lot of space for other item as there will be entires in the vtable + */ if (type() == Item::COND_ITEM && ((Item_cond*) this)->functype() == Item_func::COND_AND_FUNC) { @@ -9344,6 +9350,8 @@ Item_field::excl_dep_on_grouping_fields(st_select_lex *sel) This is used mostly for OR conjuncts where we need to make sure that the entire OR conjunct contains only one column, so that we may get accurate estimates. + An example with top level OR conjunct would be: + WHERE A=1 or A between 100 and 200 or A > 1000 @retval TRUE : the formula does not depend on one column @@ -10800,3 +10808,16 @@ bool Item::cleanup_excluding_immutables_processor (void *arg) return false; } } + + +bool Item::is_non_const_field_item() +{ + /* + calling real_item() here so that if the item is a REF_ITEM + then we would get the item field it is referring to + */ + Item *field_item= real_item(); + if (field_item->type() == Item::FIELD_ITEM && !field_item->const_item()) + return true; + return false; +} |