From a9608b196d2675f790079009d7b2ca4d80a93dbc Mon Sep 17 00:00:00 2001
From: Sergey Petrunia <sergefp@mysql.com>
Date: Wed, 28 Jan 2009 22:18:27 +0300
Subject: [PATCH] BUG#37822: Correlated subquery with IN and IS UNKNOWN
 provides wrong result Item_in_optimizer::is_null() evaluated "NULL IN (SELECT
 ...)" to NULL regardless of whether subquery produced any records, this was a
 documented limitation.

The limitation has been removed (see bugs 8804, 24085, 24127) now
Item_in_optimizer::val_int() correctly handles all cases with NULLs. Make
Item_in_optimizer::is_null() invoke val_int() to return correct values for
"NULL IN (SELECT ...)".


mysql-test/r/subselect.result:
  BUG#37822: Correlated subquery with IN and IS UNKNOWN provides wrong result
  - Testcase
mysql-test/t/subselect.test:
  BUG#37822: Correlated subquery with IN and IS UNKNOWN provides wrong result
  - Testcase
---
 mysql-test/r/subselect.result | 36 +++++++++++++++++++++++++++++++++++
 mysql-test/t/subselect.test   | 35 ++++++++++++++++++++++++++++++++++
 sql/item_cmpfunc.cc           |  4 ++--
 3 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index c1c81847b13..d38387a356f 100644
--- a/mysql-test/r/subselect.result
+++ b/mysql-test/r/subselect.result
@@ -4478,4 +4478,40 @@ WHERE 1 IN (SELECT id FROM t1) WITH CHECK OPTION;
 DELETE FROM v3;
 DROP VIEW v1,v2,v3;
 DROP TABLE t1,t2;
+#
+# BUG#37822: Correlated subquery with IN and IS UNKNOWN provides wrong result
+# 
+create table t1(id integer primary key, g integer, v integer, s char(1));
+create table t2(id integer primary key, g integer, v integer, s char(1));
+insert into t1 values
+(10, 10, 10,   'l'),
+(20, 20, 20,   'l'),
+(40, 40, 40,   'l'),
+(41, 40, null, 'l'),
+(50, 50, 50,   'l'),
+(51, 50, null, 'l'),
+(60, 60, 60,   'l'),
+(61, 60, null, 'l'),
+(70, 70, 70,   'l'),
+(90, 90, null, 'l');
+insert into t2 values
+(10, 10, 10,   'r'),
+(30, 30, 30,   'r'),
+(50, 50, 50,   'r'),
+(60, 60, 60,   'r'),
+(61, 60, null, 'r'),
+(70, 70, 70,   'r'),
+(71, 70, null, 'r'),
+(80, 80, 80,   'r'),
+(81, 80, null, 'r'),
+(100,100,null, 'r');
+select *
+from t1
+where v in(select v
+from t2
+where t1.g=t2.g) is unknown;
+id	g	v	s
+51	50	NULL	l
+61	60	NULL	l
+drop table t1, t2;
 End of 5.1 tests.
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index 493857fb463..b625d49415d 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -3391,4 +3391,39 @@ DELETE FROM v3;
 DROP VIEW v1,v2,v3;
 DROP TABLE t1,t2;
 
+--echo #
+--echo # BUG#37822: Correlated subquery with IN and IS UNKNOWN provides wrong result
+--echo #
+create table t1(id integer primary key, g integer, v integer, s char(1));
+create table t2(id integer primary key, g integer, v integer, s char(1));
+insert into t1 values
+  (10, 10, 10,   'l'),
+  (20, 20, 20,   'l'),
+  (40, 40, 40,   'l'),
+  (41, 40, null, 'l'),
+  (50, 50, 50,   'l'),
+  (51, 50, null, 'l'),
+  (60, 60, 60,   'l'),
+  (61, 60, null, 'l'),
+  (70, 70, 70,   'l'),
+  (90, 90, null, 'l');
+insert into t2 values
+  (10, 10, 10,   'r'),
+  (30, 30, 30,   'r'),
+  (50, 50, 50,   'r'),
+  (60, 60, 60,   'r'),
+  (61, 60, null, 'r'),
+  (70, 70, 70,   'r'),
+  (71, 70, null, 'r'),
+  (80, 80, 80,   'r'),
+  (81, 80, null, 'r'),
+  (100,100,null, 'r');
+
+select *
+from t1
+where v in(select v
+           from t2
+           where t1.g=t2.g) is unknown;
+drop table t1, t2;
+
 --echo End of 5.1 tests.
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 813e50e0693..bd90dd81365 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1623,8 +1623,8 @@ void Item_in_optimizer::cleanup()
 
 bool Item_in_optimizer::is_null()
 {
-  cache->store(args[0]);
-  return (null_value= (cache->null_value || args[1]->is_null()));
+  val_int();
+  return null_value;
 }