Fixed bug mdev-5204.

Always use the value of table::file->stats.records when checking
whether a table with HA_STATS_RECORDS_IS_EXACT flag contains not
more than 1 record.

1 files changed, 36 insertions, 0 deletions

diff --git a/mysql-test/r/stat_tables.result b/mysql-test/r/stat_tables.result
index 6905725a6a2..63c65e23c19 100644
--- a/mysql-test/r/stat_tables.result
+++ b/mysql-test/r/stat_tables.result
@@ -381,3 +381,39 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
 DROP TABLE t1;
 set use_stat_tables=@save_use_stat_tables;
+#
+# Bug mdev-5204: invalid impossible where after reading const tables  
+#                when use_stat_tables = 'preferably'
+#
+set use_stat_tables = 'preferably';
+CREATE TABLE t1 (id int PRIMARY KEY) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+ANALYZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+CREATE TABLE t2 (name char(3)) ENGINE=MyISAM;
+ANALYZE TABLE t2;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	Table is already up to date
+INSERT INTO t2 VALUES ('USA'),('AUS');
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+id	name
+1	AUS
+EXPLAIN
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	Using index
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	0	Using where
+ANALYZE TABLE t2;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+id	name
+1	AUS
+EXPLAIN
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	Using index
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+DROP TABLE t1,t2;
+set use_stat_tables=@save_use_stat_tables;