MDEV-19790 Wrong result for query with outer join and IS NOT TRUE predicate

           in where clause

The classes Item_func_isnottrue and Item_func_isnotfalse inherited the
implementation of the eval_not_null_tables method from the Item_func
class. As a result the not_null_tables_cache was set incorrectly for
the objects of these classes. It led to improper conversion of outer
joins to inner joins when the where clause of the processed query
contained IS NOT TRUE or IS NOT FALSE predicates. The coverted query
in many cases produced a wrong result set.

Author: igorbabaev

mysql-test/r/join_outer.result

@@ -2353,7 +2353,7 @@ t1.b1+'0'	t2.b2 + '0'
 0	0
 1	1
 DROP TABLE t1, t2;
-set @join_cache_level= @save_join_cache_level;
+set @@join_cache_level= @save_join_cache_level;
 #
 # MDEV-14779: using left join causes incorrect results with materialization and derived tables
 #
@@ -2418,5 +2418,39 @@ WHERE tb1.pk = 40
 ORDER BY tb1.i1;
 v2
 DROP TABLE t1,t2;
+#
+# MDEV-19790 : IS NOT TRUE / IS NOT FALSE predicates over
+#              inner tables of outer joins
+#
+create table t1 (a int);
+create table t2 (b int);
+insert into t1 values (3), (7), (1);
+insert into t2 values (7), (4), (3);
+select * from t1 left join t2 on a=b;
+a	b
+3	3
+7	7
+1	NULL
+select * from t1 left join t2 on a=b where (b > 3) is not true;
+a	b
+3	3
+1	NULL
+explain extended select * from t1 left join t2 on a=b where (b > 3) is not true;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`b` = `test`.`t1`.`a`)) where ((`test`.`t2`.`b` > 3) is not true)
+select * from t1 left join t2 on a=b where (b > 3) is not false;
+a	b
+7	7
+1	NULL
+explain extended select * from t1 left join t2 on a=b where (b > 3) is not false;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`b` = `test`.`t1`.`a`)) where ((`test`.`t2`.`b` > 3) is not false)
+drop table t1,t2;
 # end of 5.5 tests
 SET optimizer_switch=@save_optimizer_switch;

mysql-test/r/join_outer_jcl6.result

@@ -2364,7 +2364,7 @@ t1.b1+'0'	t2.b2 + '0'
 0	0
 1	1
 DROP TABLE t1, t2;
-set @join_cache_level= @save_join_cache_level;
+set @@join_cache_level= @save_join_cache_level;
 #
 # MDEV-14779: using left join causes incorrect results with materialization and derived tables
 #
@@ -2429,6 +2429,40 @@ WHERE tb1.pk = 40
 ORDER BY tb1.i1;
 v2
 DROP TABLE t1,t2;
+#
+# MDEV-19790 : IS NOT TRUE / IS NOT FALSE predicates over
+#              inner tables of outer joins
+#
+create table t1 (a int);
+create table t2 (b int);
+insert into t1 values (3), (7), (1);
+insert into t2 values (7), (4), (3);
+select * from t1 left join t2 on a=b;
+a	b
+7	7
+3	3
+1	NULL
+select * from t1 left join t2 on a=b where (b > 3) is not true;
+a	b
+3	3
+1	NULL
+explain extended select * from t1 left join t2 on a=b where (b > 3) is not true;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`b` = `test`.`t1`.`a`)) where ((`test`.`t2`.`b` > 3) is not true)
+select * from t1 left join t2 on a=b where (b > 3) is not false;
+a	b
+7	7
+1	NULL
+explain extended select * from t1 left join t2 on a=b where (b > 3) is not false;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` left join `test`.`t2` on((`test`.`t2`.`b` = `test`.`t1`.`a`)) where ((`test`.`t2`.`b` > 3) is not false)
+drop table t1,t2;
 # end of 5.5 tests
 SET optimizer_switch=@save_optimizer_switch;
 set join_cache_level=default;

mysql-test/t/join_outer.test

@@ -1895,7 +1895,7 @@ set @save_join_cache_level= @@join_cache_level;
 SET  @@join_cache_level = 3;
 SELECT t1.b1+'0' , t2.b2 + '0' FROM t1 LEFT JOIN t2 ON b1 = b2;
 DROP TABLE t1, t2;
-set @join_cache_level= @save_join_cache_level;
+set @@join_cache_level= @save_join_cache_level;
 
 --echo #
 --echo # MDEV-14779: using left join causes incorrect results with materialization and derived tables
@@ -1959,6 +1959,29 @@ ORDER BY tb1.i1;
 
 DROP TABLE t1,t2;
 
+--echo #
+--echo # MDEV-19790 : IS NOT TRUE / IS NOT FALSE predicates over
+--echo #              inner tables of outer joins
+--echo #
+
+create table t1 (a int);
+create table t2 (b int);
+insert into t1 values (3), (7), (1);
+insert into t2 values (7), (4), (3);
+select * from t1 left join t2 on a=b;
+
+let $q=
+select * from t1 left join t2 on a=b where (b > 3) is not true;
+eval $q;
+eval explain extended $q;
+
+let $q=
+select * from t1 left join t2 on a=b where (b > 3) is not false;
+eval $q;
+eval explain extended $q;
+
+drop table t1,t2;
+
 --echo # end of 5.5 tests
 
 SET optimizer_switch=@save_optimizer_switch;

sql/item_cmpfunc.h

@@ -183,6 +183,8 @@ class Item_func_isnottrue : public Item_func_truth
   Item_func_isnottrue(Item *a) : Item_func_truth(a, true, false) {}
   ~Item_func_isnottrue() {}
   virtual const char* func_name() const { return "isnottrue"; }
+  bool eval_not_null_tables(uchar *opt_arg)
+  { not_null_tables_cache= 0; return false; }
 };
 
 
@@ -209,6 +211,8 @@ class Item_func_isnotfalse : public Item_func_truth
   Item_func_isnotfalse(Item *a) : Item_func_truth(a, false, false) {}
   ~Item_func_isnotfalse() {}
   virtual const char* func_name() const { return "isnotfalse"; }
+  bool eval_not_null_tables(uchar *opt_arg)
+  { not_null_tables_cache= 0; return false; }
 };