Fixed LP bug #901478.

If the duplicate elimination strategy is used for a semi-join and potentially
one of the block-based join algorithms can be employed to join the inner
tables of the semi-join then sorting of the head (first non-constant) table
for a query with ORDER BY / GROUP BY cannot be used.

mysql-test/r/join_cache.result

@@ -5313,4 +5313,83 @@ a	b	c	d
 SET SESSION join_cache_level = DEFAULT;
 SET optimizer_switch=@tmp_optimizer_switch;
 DROP TABLE t1,t2,t3;
+#
+# Bug #901478: semijoin + ORDER BY + join_cache_level=4|6 
+#
+CREATE TABLE t1 (a char(1));
+INSERT INTO t1 VALUES ('x');
+CREATE TABLE t2 (a int, b int, c int, KEY(a), KEY(b), KEY(c));
+INSERT INTO t2 VALUES
+(9,1,0), (7,2,8), (2,3,5), (4,2,9), (8,3,8), (3,4,1), (5,5,4);
+CREATE TABLE t3 (a CHAR(1));
+INSERT INTO t3 VALUES ('x');
+CREATE TABLE t4 (a int, b int, c int, KEY(b), KEY(c));
+INSERT INTO t4 VALUES
+(9,1,0), (7,2,8), (2,3,5), (4,2,9), (8,3,8), (3,4,1), (5,5,4);
+INSERT INTO t4 VALUES
+(19,11,10), (17,12,18), (12,13,15), (14,12,19),
+(18,13,18), (13,14,11), (15,15,14);
+SET @tmp_optimizer_switch=@@optimizer_switch;
+SET @@optimizer_switch='semijoin=on';
+SET @@optimizer_switch='firstmatch=off';
+SET @@optimizer_switch='mrr=off';
+SET @@optimizer_switch='semijoin_with_cache=off';
+set join_cache_level=1;
+EXPLAIN
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	Using filesort
+1	PRIMARY	t3	system	NULL	NULL	NULL	NULL	1	
+1	PRIMARY	t2	range	a,c	a	5	NULL	1	Using index condition; Using where
+1	PRIMARY	t4	ref	c	c	5	test.t2.c	2	Using where; Start temporary; End temporary
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+a	a	b	c
+x	4	2	9
+x	5	5	4
+set join_cache_level=4;
+EXPLAIN
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	Using temporary; Using filesort
+1	PRIMARY	t3	system	NULL	NULL	NULL	NULL	1	
+1	PRIMARY	t2	range	a,c	a	5	NULL	1	Using index condition; Using where
+1	PRIMARY	t4	ref	c	c	5	test.t2.c	2	Using where; Start temporary; End temporary
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+a	a	b	c
+x	4	2	9
+x	5	5	4
+SET @@optimizer_switch='semijoin_with_cache=on';
+set join_cache_level=6;
+EXPLAIN
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	Using temporary; Using filesort
+1	PRIMARY	t3	system	NULL	NULL	NULL	NULL	1	
+1	PRIMARY	t2	range	a,c	a	5	NULL	1	Using index condition; Using where
+1	PRIMARY	t4	ref	c	c	5	test.t2.c	2	Using where; Start temporary; End temporary
+SELECT * FROM t1,t2
+WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+t2.a BETWEEN 4 and 5
+ORDER BY t2.b;
+a	a	b	c
+x	4	2	9
+x	5	5	4
+SET join_cache_level = DEFAULT;
+SET optimizer_switch=@tmp_optimizer_switch;
+DROP TABLE t1,t2,t3,t4;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/join_cache.test

@@ -3361,5 +3361,68 @@ SET optimizer_switch=@tmp_optimizer_switch;
 
 DROP TABLE t1,t2,t3;
 
+--echo #
+--echo # Bug #901478: semijoin + ORDER BY + join_cache_level=4|6 
+--echo #
+
+CREATE TABLE t1 (a char(1));
+INSERT INTO t1 VALUES ('x');
+CREATE TABLE t2 (a int, b int, c int, KEY(a), KEY(b), KEY(c));
+INSERT INTO t2 VALUES
+  (9,1,0), (7,2,8), (2,3,5), (4,2,9), (8,3,8), (3,4,1), (5,5,4);
+CREATE TABLE t3 (a CHAR(1));
+INSERT INTO t3 VALUES ('x');
+CREATE TABLE t4 (a int, b int, c int, KEY(b), KEY(c));
+INSERT INTO t4 VALUES
+  (9,1,0), (7,2,8), (2,3,5), (4,2,9), (8,3,8), (3,4,1), (5,5,4);
+INSERT INTO t4 VALUES
+  (19,11,10), (17,12,18), (12,13,15), (14,12,19),
+  (18,13,18), (13,14,11), (15,15,14);
+
+SET @tmp_optimizer_switch=@@optimizer_switch;
+SET @@optimizer_switch='semijoin=on';
+SET @@optimizer_switch='firstmatch=off';
+SET @@optimizer_switch='mrr=off';
+SET @@optimizer_switch='semijoin_with_cache=off';
+
+set join_cache_level=1;
+EXPLAIN
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+
+set join_cache_level=4;
+EXPLAIN
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+
+SET @@optimizer_switch='semijoin_with_cache=on';
+set join_cache_level=6;
+EXPLAIN
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+SELECT * FROM t1,t2
+  WHERE t2.c IN (SELECT c FROM t3,t4 WHERE t4.a < 10) AND
+        t2.a BETWEEN 4 and 5
+  ORDER BY t2.b;
+
+SET join_cache_level = DEFAULT;
+SET optimizer_switch=@tmp_optimizer_switch;
+
+DROP TABLE t1,t2,t3,t4;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/opt_subselect.cc

@@ -4138,6 +4138,16 @@ int setup_semijoin_dups_elimination(JOIN *join, ulonglong options,
           {
             /* Looks like we'll be using join buffer */
             first_table= join->const_tables;
+            /* 
+              Make sure that possible sorting of rows from the head table 
+              is not to be employed.
+            */
+            if (join->get_sort_by_join_tab())
+	    {
+              join->simple_order= 0;
+              join->simple_group= 0;
+              join->need_tmp= join->test_if_need_tmp_table();
+            }
             break;
           }
         }

sql/sql_select.cc

@@ -1524,22 +1524,7 @@ JOIN::optimize()
     }
   }
 
-  /*
-    Check if we need to create a temporary table.
-    This has to be done if all tables are not already read (const tables)
-    and one of the following conditions holds:
-    - We are using DISTINCT (simple distinct's are already optimized away)
-    - We are using an ORDER BY or GROUP BY on fields not in the first table
-    - We are using different ORDER BY and GROUP BY orders
-    - The user wants us to buffer the result.
-    When the WITH ROLLUP modifier is present, we cannot skip temporary table
-    creation for the DISTINCT clause just because there are only const tables.
-  */
-  need_tmp= ((const_tables != table_count &&
-	     ((select_distinct || !simple_order || !simple_group) ||
-	      (group_list && order) ||
-	      test(select_options & OPTION_BUFFER_RESULT))) ||
-             (rollup.state != ROLLUP::STATE_NONE && select_distinct));
+  need_tmp= test_if_need_tmp_table();
 
   /*
     If the hint FORCE INDEX FOR ORDER BY/GROUP BY is used for the table

sql/sql_select.h

@@ -1318,6 +1318,25 @@ class JOIN :public Sql_alloc
     return test(allowed_join_cache_types & JOIN_CACHE_HASHED_BIT) &&
            max_allowed_join_cache_level > JOIN_CACHE_HASHED_BIT;
   }
+  /*
+    Check if we need to create a temporary table.
+    This has to be done if all tables are not already read (const tables)
+    and one of the following conditions holds:
+    - We are using DISTINCT (simple distinct's are already optimized away)
+    - We are using an ORDER BY or GROUP BY on fields not in the first table
+    - We are using different ORDER BY and GROUP BY orders
+    - The user wants us to buffer the result.
+    When the WITH ROLLUP modifier is present, we cannot skip temporary table
+    creation for the DISTINCT clause just because there are only const tables.
+  */
+  bool test_if_need_tmp_table()
+  {
+    return ((const_tables != table_count &&
+	    ((select_distinct || !simple_order || !simple_group) ||
+	     (group_list && order) ||
+	     test(select_options & OPTION_BUFFER_RESULT))) ||
+            (rollup.state != ROLLUP::STATE_NONE && select_distinct));
+  }
   bool choose_subquery_plan(table_map join_tables);
   void get_partial_cost_and_fanout(int end_tab_idx,
                                    table_map filter_map,