Fixed bug mdev-5415.

Do not calculate selectivity of conditions for the tables of the information schema.

mysql-test/r/selectivity.result

@@ -1158,3 +1158,11 @@ Note	1003	select `test`.`t1`.`i1` AS `i1` from `test`.`t1` semi join (`test`.`t2
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
 DROP TABLE t1,t2,t3;
 set use_stat_tables=@save_use_stat_tables;
+#
+# Bug mdev-5415: query over an information schema table   
+#                when optimizer_use_condition_selectivity=3
+#
+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;

mysql-test/r/selectivity_innodb.result

@@ -1166,5 +1166,13 @@ Note	1003	select `test`.`t1`.`i1` AS `i1` from `test`.`t1` semi join (`test`.`t2
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
 DROP TABLE t1,t2,t3;
 set use_stat_tables=@save_use_stat_tables;
+#
+# Bug mdev-5415: query over an information schema table   
+#                when optimizer_use_condition_selectivity=3
+#
+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;
 set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/selectivity.test

@@ -739,3 +739,14 @@ DROP TABLE t1,t2,t3;
 
 set use_stat_tables=@save_use_stat_tables;
 
+--echo #
+--echo # Bug mdev-5415: query over an information schema table   
+--echo #                when optimizer_use_condition_selectivity=3
+--echo #
+
+set optimizer_use_condition_selectivity = 3;
+
+SELECT * FROM INFORMATION_SCHEMA.TRIGGERS WHERE SQL_MODE != '';
+
+set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+

sql/opt_range.cc

@@ -3411,6 +3411,9 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
   if (table_records == 0)
     DBUG_RETURN(FALSE);
 
+  if (table->pos_in_table_list->schema_table)
+    DBUG_RETURN(FALSE);
+  
   if (thd->variables.optimizer_use_condition_selectivity > 2 &&
       !bitmap_is_clear_all(used_fields))
   {