Fixed bug mdev-7316.

The function table_cond_selectivity() should take into account that condition selectivity
for some fields can be set to 0.

1 files changed, 29 insertions, 0 deletions

diff --git a/mysql-test/t/selectivity.test b/mysql-test/t/selectivity.test
index 77ee5f49bef..c46ff69295f 100644
--- a/mysql-test/t/selectivity.test
+++ b/mysql-test/t/selectivity.test
@@ -942,5 +942,34 @@ set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivit
 
 drop table t0,t1,t2;
 
+--echo #
+--echo # Bug mdev-7316: a conjunct in WHERE with selectivity == 0
+--echo #
+
+CREATE TABLE t1 (a varchar(16), b int, PRIMARY KEY(a), KEY(b)) ENGINE=INNODB;
+INSERT INTO t1 VALUES
+  ('USAChinese',10), ('USAEnglish',20), ('USAFrench',30);
+
+CREATE TABLE t2 (i int) ENGINE=INNODB;
+INSERT INTO t2 VALUES
+  (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(1),(2),(3),(4);
+
+ANALYZE TABLE t1, t2;
+
+set use_stat_tables='preferably';
+set optimizer_use_condition_selectivity=3;
+
+EXPLAIN EXTENDED
+SELECT * FROM t1, t2
+  WHERE  a <> 'USARussian' AND b IS NULL;
+
+SELECT * FROM t1, t2
+  WHERE a <> 'USARussian' AND b IS NULL;
+
+set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+
+DROP TABLE t1,t2;
+
+
 set use_stat_tables=@save_use_stat_tables;