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.

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;

mysql-test/r/stat_tables_innodb.result

@@ -408,5 +408,41 @@ 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;
 set optimizer_switch=@save_optimizer_switch_for_stat_tables_test;
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/stat_tables.test

@@ -205,3 +205,31 @@ DROP TABLE t1;
 
 set use_stat_tables=@save_use_stat_tables;
 
+--echo #
+--echo # Bug mdev-5204: invalid impossible where after reading const tables  
+--echo #                when use_stat_tables = 'preferably'
+--echo #
+
+set use_stat_tables = 'preferably';
+
+CREATE TABLE t1 (id int PRIMARY KEY) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+ANALYZE TABLE t1;
+
+CREATE TABLE t2 (name char(3)) ENGINE=MyISAM;
+ANALYZE TABLE t2;
+INSERT INTO t2 VALUES ('USA'),('AUS');
+
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+EXPLAIN
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+
+ANALYZE TABLE t2;
+
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+EXPLAIN
+SELECT * FROM t1 STRAIGHT_JOIN t2 WHERE name IN ( 'AUS','YEM' ) AND id = 1;
+
+DROP TABLE t1,t2;
+
+set use_stat_tables=@save_use_stat_tables;

sql/sql_select.cc

@@ -3691,7 +3691,7 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
 	// All dep. must be constants
 	if (s->dependent & ~(found_const_table_map))
 	  continue;
-	if (table->stat_records() <= 1L &&
+	if (table->file->stats.records <= 1L &&
 	    (table->file->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT) &&
             !table->pos_in_table_list->embedding &&
 	      !((outer_join & table->map) &&