MWL#68 Subquery optimization: Efficient NOT IN execution with NULLs

This patch does three things:
- It adds the possibility to force the execution of top-level [NOT] IN
  subquery predicates via the IN=>EXISTS transformation. This is done by
  setting both optimizer switches partial_match_rowid_merge and
  partial_match_table_scan to "off".
- It adjusts all test cases where the complete optimizer_switch is
  selected because now we have two more switches.
- For those test cases where the plan changes because of the new available
  strategies, we switch off both partial match strategies in order to
  force the "old" IN=>EXISTS strategy. This is done because most of these
  test cases specifically test bugs in this strategy.

sql/opt_subselect.cc:
  Adds the possibility to force the execution of top-level [NOT] IN
  subquery predicates via the IN=>EXISTS transformation. This is done by
  setting both optimizer switches partial_match_rowid_merge and
  partial_match_table_scan to "off".

1 files changed, 9 insertions, 0 deletions

diff --git a/mysql-test/t/subselect3.test b/mysql-test/t/subselect3.test
index 8ae73587d6e..fa1f916261c 100644
--- a/mysql-test/t/subselect3.test
+++ b/mysql-test/t/subselect3.test
@@ -59,9 +59,13 @@ select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 show status like 'Handler_read_rnd_next';
 select ' ^ This must show 11' Z;
 
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
+
 # This must show trigcond:
 explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 
+set @@optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 
 # 
@@ -529,6 +533,9 @@ SELECT a, MAX(b),
 
 DROP TABLE t1, t2;
 
+# The next three test cases must be executed with the IN=>EXISTS strategy
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 
 #
 # Bug #27870: crash of an equijoin query with WHERE condition containing 
@@ -588,6 +595,8 @@ EXPLAIN SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
 
 DROP TABLE t1, t2;
 
+set @@optimizer_switch=@save_optimizer_switch;
+
 #
 # Bug #34763: item_subselect.cc:1235:Item_in_subselect::row_value_transformer:
 #             Assertion failed, unexpected error message: