Fix of LP BUG#793589 Wrong result with double ORDER BY

Problem was in caching 'eq_ref' dependency between calls of remove_const() for ORDER BY and GROUP BY lists.

mysql-test/r/order_by.result

@@ -1672,3 +1672,57 @@ select 1 order by max(1) + min(1);
 1
 1
 End of 5.1 tests
+#
+# Fix of LP BUG#793589 Wrong result with double ORDER BY
+#
+CREATE TABLE t1 ( b int) ;
+INSERT INTO t1 VALUES (8),(9);
+CREATE TABLE t2 ( a int, b int, PRIMARY KEY (a)) ;
+INSERT INTO t2 VALUES (6,7),(7,7),(8,1),(9,7),(10,1),(11,5),(12,2),(13,0),(14,1),(15,8),(16,1),(17,1),(18,9),(19,1),(20,5);
+SELECT t2.b AS field1 FROM t1, t2 WHERE t1.b = t2.a GROUP BY field1 ORDER BY t1.b, field1;
+field1
+1
+7
+SELECT t2.b, t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b, t2.b;
+b	b
+1	8
+7	9
+SELECT t2.b,t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+b	b
+1	8
+7	9
+SELECT t2.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+b
+1
+7
+# field1 removed from ORDER BY
+explain extended
+SELECT t2.b AS field1 FROM t1, t2 WHERE t1.b = t2.a GROUP BY field1 ORDER BY t1.b, field1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	100.00	
+Warnings:
+Note	1003	select `test`.`t2`.`b` AS `field1` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`a` = `test`.`t1`.`b`) group by `test`.`t2`.`b` order by `test`.`t1`.`b`
+explain extended
+SELECT t2.b, t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b, t2.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	100.00	
+Warnings:
+Note	1003	select `test`.`t2`.`b` AS `b`,`test`.`t1`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`a` = `test`.`t1`.`b`) group by `test`.`t2`.`b` order by `test`.`t1`.`b`
+explain extended
+SELECT t2.b,t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	100.00	
+Warnings:
+Note	1003	select `test`.`t2`.`b` AS `b`,`test`.`t1`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`a` = `test`.`t1`.`b`) group by `test`.`t2`.`b` order by `test`.`t1`.`b`
+explain extended
+SELECT t2.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	100.00	
+Warnings:
+Note	1003	select `test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`a` = `test`.`t1`.`b`) group by `test`.`t2`.`b` order by `test`.`t1`.`b`
+drop table t1,t2;
+End of 5.2 tests

mysql-test/t/order_by.test

@@ -1518,3 +1518,32 @@ DROP TABLE t1;
 select 1 order by max(1) + min(1);
 
 --echo End of 5.1 tests
+
+--echo #
+--echo # Fix of LP BUG#793589 Wrong result with double ORDER BY
+--echo #
+CREATE TABLE t1 ( b int) ;
+INSERT INTO t1 VALUES (8),(9);
+
+CREATE TABLE t2 ( a int, b int, PRIMARY KEY (a)) ;
+INSERT INTO t2 VALUES (6,7),(7,7),(8,1),(9,7),(10,1),(11,5),(12,2),(13,0),(14,1),(15,8),(16,1),(17,1),(18,9),(19,1),(20,5);
+
+SELECT t2.b AS field1 FROM t1, t2 WHERE t1.b = t2.a GROUP BY field1 ORDER BY t1.b, field1;
+SELECT t2.b, t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b, t2.b;
+SELECT t2.b,t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+SELECT t2.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+
+--echo # field1 removed from ORDER BY
+explain extended
+SELECT t2.b AS field1 FROM t1, t2 WHERE t1.b = t2.a GROUP BY field1 ORDER BY t1.b, field1;
+explain extended
+SELECT t2.b, t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b, t2.b;
+explain extended
+SELECT t2.b,t1.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+explain extended
+SELECT t2.b FROM t1, t2 WHERE t1.b = t2.a GROUP BY t2.b ORDER BY t1.b;
+
+
+drop table t1,t2;
+
+--echo End of 5.2 tests

sql/sql_select.cc

@@ -7368,6 +7368,15 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
   table_map ref;
   DBUG_ENTER("remove_const");
 
+  /*
+    Cleanup to avoid interference of calls of this function for
+    ORDER BY and GROUP BY
+  */
+  for (JOIN_TAB *tab= join->join_tab + join->const_tables;
+       tab < join->join_tab + join->tables;
+       tab++)
+    tab->cached_eq_ref_table= FALSE;
+
   prev_ptr= &first_order;
   *simple_order= *join->join_tab[join->const_tables].on_expr_ref ? 0 : 1;