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| author | sergefp@mysql.com <> | 2006-10-31 20:51:09 +0300 |
|---|---|---|
| committer | sergefp@mysql.com <> | 2006-10-31 20:51:09 +0300 |
| commit | 54a713aac54f97a19b3c90afdfca6122c506c1cf (patch) | |
| tree | 9720832e2f3ce2403e51f324722b5522b5bac946 /sql/item.h | |
| parent | 2ab34bac4b9b790c6476977272e18cdeae3d186b (diff) | |
| download | mariadb-git-54a713aac54f97a19b3c90afdfca6122c506c1cf.tar.gz | |
BUG#8804: wrong results for NULL IN (SELECT ...)
Evaluate "NULL IN (SELECT ...)" in a special way: Disable pushed-down
conditions and their "consequences":
= Do full table scans instead of unique_[index_subquery] lookups.
= Change appropriate "ref_or_null" accesses to full table scans in
subquery's joins.
Also cache value of NULL IN (SELECT ...) if the SELECT is not correlated
wrt any upper select.
Diffstat (limited to 'sql/item.h')
| -rw-r--r-- | sql/item.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/sql/item.h b/sql/item.h index 0cfb0b01fd8..566daa1aaee 100644 --- a/sql/item.h +++ b/sql/item.h @@ -1959,6 +1959,16 @@ public: class Item_in_subselect; + +/* + An object of this class: + - Converts val_XXX() calls to ref->val_XXX_result() calls, like Item_ref. + - Sets owner->was_null=TRUE if it has returned a NULL value from any + val_XXX() function. This allows to inject an Item_ref_null_helper + object into subquery and then check if the subquery has produced a row + with NULL value. +*/ + class Item_ref_null_helper: public Item_ref { protected: |