Fixed bug mdev-5630.

The function calculate_cond_selectivity_for_table() must consider
the case when the key range tree returned by the call of get_mm_tree()
is of the type SEL_TREE::ALWAYS.

mysql-test/r/selectivity.result

@@ -1166,3 +1166,21 @@ set optimizer_use_condition_selectivity = 3;
 SELECT * FROM INFORMATION_SCHEMA.TRIGGERS WHERE SQL_MODE != '';
 TRIGGER_CATALOG	TRIGGER_SCHEMA	TRIGGER_NAME	EVENT_MANIPULATION	EVENT_OBJECT_CATALOG	EVENT_OBJECT_SCHEMA	EVENT_OBJECT_TABLE	ACTION_ORDER	ACTION_CONDITION	ACTION_STATEMENT	ACTION_ORIENTATION	ACTION_TIMING	ACTION_REFERENCE_OLD_TABLE	ACTION_REFERENCE_NEW_TABLE	ACTION_REFERENCE_OLD_ROW	ACTION_REFERENCE_NEW_ROW	CREATED	SQL_MODE	DEFINER	CHARACTER_SET_CLIENT	COLLATION_CONNECTION	DATABASE_COLLATION
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+#
+# Bug mdev-5630: always true conjunctive condition   
+#                when optimizer_use_condition_selectivity=3
+#
+set use_stat_tables = 'preferably';
+set optimizer_use_condition_selectivity = 3;
+CREATE TABLE t1 (a int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (10);
+CREATE TABLE t2 (id int, flag char(1), INDEX(id)) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (100,'0'),(101,'1');
+ANALYZE TABLE t1, t2;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+test.t2	analyze	status	OK
+SELECT * FROM t1, t2 WHERE id = a AND ( a = 16 OR flag AND a != 6 );
+a	id	flag
+DROP TABLE t1,t2;
+set use_stat_tables=@save_use_stat_tables;

mysql-test/r/selectivity_innodb.result

@@ -1174,5 +1174,23 @@ set optimizer_use_condition_selectivity = 3;
 SELECT * FROM INFORMATION_SCHEMA.TRIGGERS WHERE SQL_MODE != '';
 TRIGGER_CATALOG	TRIGGER_SCHEMA	TRIGGER_NAME	EVENT_MANIPULATION	EVENT_OBJECT_CATALOG	EVENT_OBJECT_SCHEMA	EVENT_OBJECT_TABLE	ACTION_ORDER	ACTION_CONDITION	ACTION_STATEMENT	ACTION_ORIENTATION	ACTION_TIMING	ACTION_REFERENCE_OLD_TABLE	ACTION_REFERENCE_NEW_TABLE	ACTION_REFERENCE_OLD_ROW	ACTION_REFERENCE_NEW_ROW	CREATED	SQL_MODE	DEFINER	CHARACTER_SET_CLIENT	COLLATION_CONNECTION	DATABASE_COLLATION
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+#
+# Bug mdev-5630: always true conjunctive condition   
+#                when optimizer_use_condition_selectivity=3
+#
+set use_stat_tables = 'preferably';
+set optimizer_use_condition_selectivity = 3;
+CREATE TABLE t1 (a int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (10);
+CREATE TABLE t2 (id int, flag char(1), INDEX(id)) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (100,'0'),(101,'1');
+ANALYZE TABLE t1, t2;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+test.t2	analyze	status	OK
+SELECT * FROM t1, t2 WHERE id = a AND ( a = 16 OR flag AND a != 6 );
+a	id	flag
+DROP TABLE t1,t2;
+set use_stat_tables=@save_use_stat_tables;
 set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/selectivity.test

@@ -750,3 +750,25 @@ SELECT * FROM INFORMATION_SCHEMA.TRIGGERS WHERE SQL_MODE != '';
 
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
 
+--echo #
+--echo # Bug mdev-5630: always true conjunctive condition   
+--echo #                when optimizer_use_condition_selectivity=3
+--echo #
+
+set use_stat_tables = 'preferably';
+set optimizer_use_condition_selectivity = 3;
+
+CREATE TABLE t1 (a int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (10);
+
+CREATE TABLE t2 (id int, flag char(1), INDEX(id)) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (100,'0'),(101,'1');
+
+ANALYZE TABLE t1, t2;
+
+SELECT * FROM t1, t2 WHERE id = a AND ( a = 16 OR flag AND a != 6 );
+
+DROP TABLE t1,t2;
+
+set use_stat_tables=@save_use_stat_tables;
+

sql/opt_range.cc

@@ -3460,6 +3460,11 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
       table->reginfo.impossible_range= 1;
       goto free_alloc;
     }  
+    else if (tree->type == SEL_TREE::ALWAYS)
+    {
+      rows= table_records;
+      goto free_alloc;
+    }        
     else if (tree->type == SEL_TREE::MAYBE)
     {
       rows= table_records;