Merge gkodinov@bk-internal.mysql.com:/home/bk/mysql-5.0-opt (625c44fe) · Commits · Software / OSDI20 Artifacts / mariadb

mysql-test/r/status.result

+48 −0

Original line number	Diff line number	Diff line
		@@ -43,3 +43,51 @@ SHOW STATUS LIKE 'max_used_connections';
		Variable_name Value
		Max_used_connections 4
		SET GLOBAL thread_cache_size=@save_thread_cache_size;
		CREATE TABLE t1 ( a INT );
		INSERT INTO t1 VALUES (1), (2);
		SELECT a FROM t1 LIMIT 1;
		a
		1
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 2.402418
		EXPLAIN SELECT a FROM t1;
		id select_type table type possible_keys key key_len ref rows Extra
		1 SIMPLE t1 ALL NULL NULL NULL NULL 2
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 2.402418
		SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
		a
		1
		2
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 0.000000
		EXPLAIN SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
		id select_type table type possible_keys key key_len ref rows Extra
		1 PRIMARY t1 ALL NULL NULL NULL NULL 2
		2 UNION t1 ALL NULL NULL NULL NULL 2
		NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL Using filesort
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 0.000000
		SELECT a IN (SELECT a FROM t1) FROM t1 LIMIT 1;
		a IN (SELECT a FROM t1)
		1
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 0.000000
		SELECT (SELECT a FROM t1 LIMIT 1) x FROM t1 LIMIT 1;
		x
		1
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 0.000000
		SELECT * FROM t1 a, t1 b LIMIT 1;
		a a
		1 1
		SHOW SESSION STATUS LIKE 'Last_query_cost';
		Variable_name Value
		Last_query_cost 4.805836
		DROP TABLE t1;

mysql-test/t/status.test

+32 −0

Original line number	Diff line number	Diff line
		@@ -139,4 +139,36 @@ disconnect con3;
		disconnect con2;
		disconnect con1;


		#
		# Bug #30377: EXPLAIN loses last_query_cost when used with UNION
		#

		CREATE TABLE t1 ( a INT );
		INSERT INTO t1 VALUES (1), (2);

		SELECT a FROM t1 LIMIT 1;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		EXPLAIN SELECT a FROM t1;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		EXPLAIN SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		SELECT a IN (SELECT a FROM t1) FROM t1 LIMIT 1;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		SELECT (SELECT a FROM t1 LIMIT 1) x FROM t1 LIMIT 1;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		SELECT * FROM t1 a, t1 b LIMIT 1;
		SHOW SESSION STATUS LIKE 'Last_query_cost';

		DROP TABLE t1;


		# End of 5.0 tests

sql/sql_lex.h

+22 −0

Original line number	Diff line number	Diff line
		@@ -1257,6 +1257,28 @@ typedef struct st_lex : public Query_tables_list

		void reset_n_backup_query_tables_list(Query_tables_list *backup);
		void restore_backup_query_tables_list(Query_tables_list *backup);

		/**
		@brief check if the statement is a single-level join
		@return result of the check
		@retval TRUE The statement doesn't contain subqueries, unions and
		stored procedure calls.
		@retval FALSE There are subqueries, UNIONs or stored procedure calls.
		*/
		bool is_single_level_stmt()
		{
		/*
		This check exploits the fact that the last added to all_select_list is
		on its top. So select_lex (as the first added) will be at the tail
		of the list.
		*/
		if (&select_lex == all_selects_list && !sroutines.records)
		{
		DBUG_ASSERT(!all_selects_list->next_select_in_list());
		return TRUE;
		}
		return FALSE;
		}
		} LEX;

		struct st_lex_local: public st_lex

sql/sql_select.cc

+6 −2

Original line number	Diff line number	Diff line
		@@ -4401,9 +4401,13 @@ choose_plan(JOIN *join, table_map join_tables)

		/*
		Store the cost of this query into a user variable
		Don't update last_query_cost for 'show status' command
		Don't update last_query_cost for 'show status' command.
		Don't update last_query_cost for statements that are not "flat joins" :
		i.e. they have subqueries, unions or call stored procedures.
		TODO: calculate a correct cost for a query with subqueries and UNIONs.
		*/
		if (join->thd->lex->orig_sql_command != SQLCOM_SHOW_STATUS)
		if (join->thd->lex->orig_sql_command != SQLCOM_SHOW_STATUS &&
		join->thd->lex->is_single_level_stmt())
		join->thd->status_var.last_query_cost= join->best_read;
		DBUG_RETURN(FALSE);
		}