BUG#920255: Wrong result (extra rows) with loosescan and IN subquery

The problem was that LooseScan execution code assumed that tab->key holds 
the index used for looseScan. This is only true when range or full index
scan are used. In case of ref access, the index is in tab->ref.key (and 
tab->index==0 which explains how LooseScan passed tests with ref access: they 
used one index)

Fixed by setting/using loosescan_key, which always the correct index#.

1 files changed, 19 insertions, 0 deletions

diff --git a/mysql-test/t/subselect_sj.test b/mysql-test/t/subselect_sj.test
index f34cf5ba338..afa471d5889 100644
--- a/mysql-test/t/subselect_sj.test
+++ b/mysql-test/t/subselect_sj.test
@@ -2017,5 +2017,24 @@ SELECT a, COUNT(*) FROM t1
 
 DROP TABLE t1, t2, t3;
 
+--echo #
+--echo # BUG#920255: Wrong result (extra rows) with loosescan and IN subquery
+--echo #
+CREATE TABLE t1 ( a INT PRIMARY KEY, b INT, KEY(b) );
+INSERT INTO t1 VALUES
+  (1,2),(2,1),(3,3),(4,2),(5,5),
+  (6,3),(7,1),(8,4),(9,3),(10,2);
+
+CREATE TABLE t2 ( c INT, d INT, UNIQUE KEY(c) );
+INSERT INTO t2 VALUES
+  (1,2),(2,1),(3,3),(4,2),(5,5),(6,3),(7,1);
+
+SELECT a, b, d FROM t1, t2
+WHERE ( b, d ) IN
+  ( SELECT b, d FROM t1, t2 WHERE b = c );
+
+DROP TABLE t1, t2;
+
+
 # The following command must be the last one the file 
 set optimizer_switch=@subselect_sj_tmp;