Bug #17212 results not sorted correctly by ORDER BY when using index

  * don't use join cache when the incoming data set is already ordered
    for ORDER BY
    This choice must be made because join cache will effectively
    reverse the join order and the results will be sorted by the index
    of the table that uses join cache.


mysql-test/r/innodb_mysql.result:
  Bug #17212 results not sorted correctly by ORDER BY when using index
    * Test suite for the bug
mysql-test/t/innodb_mysql.test:
  Bug #17212 results not sorted correctly by ORDER BY when using index
    * Test suite for the bug
sql/sql_select.cc:
  Bug #17212 results not sorted correctly by ORDER BY when using index
    * don't use join cache when the incoming data set is already sorted

mysql-test/r/innodb_mysql.result

@@ -54,3 +54,32 @@ c.c_id = 218 and expiredate is null;
 slai_id
 12
 drop table t1, t2;
+CREATE TABLE t1 (a int, b int, KEY b (b)) Engine=InnoDB;
+CREATE TABLE t2 (a int, b int, PRIMARY KEY  (a,b)) Engine=InnoDB;
+CREATE TABLE t3 (a int, b int, c int, PRIMARY KEY  (a), 
+UNIQUE KEY b (b,c), KEY a (a,b,c)) Engine=InnoDB;
+INSERT INTO t1 VALUES (1, 1);
+INSERT INTO t1 SELECT a + 1, b + 1 FROM t1;
+INSERT INTO t1 SELECT a + 2, b + 2 FROM t1;
+INSERT INTO t2 VALUES (1,1),(1,2),(1,3),(1,4),(1,5),(1,6),(1,7),(1,8);
+INSERT INTO t2 SELECT a + 1, b FROM t2;
+DELETE FROM t2 WHERE a = 1 AND b < 2;
+INSERT INTO t3 VALUES (1,1,1),(2,1,2);
+INSERT INTO t3 SELECT a + 2, a + 2, 3 FROM t3;
+INSERT INTO t3 SELECT a + 4, a + 4, 3 FROM t3;
+SELECT STRAIGHT_JOIN SQL_NO_CACHE t1.b, t1.a FROM t1, t3, t2 WHERE 
+t3.a = t2.a AND t2.b = t1.a AND t3.b = 1 AND t3.c IN (1, 2) 
+ORDER BY t1.b LIMIT 2;
+b	a
+1	1
+2	2
+SELECT STRAIGHT_JOIN SQL_NO_CACHE t1.b, t1.a FROM t1, t3, t2 WHERE 
+t3.a = t2.a AND t2.b = t1.a AND t3.b = 1 AND t3.c IN (1, 2) 
+ORDER BY t1.b LIMIT 5;
+b	a
+1	1
+2	2
+2	2
+3	3
+3	3
+DROP TABLE t1, t2, t3;

mysql-test/t/innodb_mysql.test

@@ -57,3 +57,36 @@ where
   c.c_id = 218 and expiredate is null;
 
 drop table t1, t2;
+
+#
+# Bug#17212: results not sorted correctly by ORDER BY when using index
+# (repeatable only w/innodb because of index props)
+#
+CREATE TABLE t1 (a int, b int, KEY b (b)) Engine=InnoDB;
+CREATE TABLE t2 (a int, b int, PRIMARY KEY  (a,b)) Engine=InnoDB;
+CREATE TABLE t3 (a int, b int, c int, PRIMARY KEY  (a), 
+  UNIQUE KEY b (b,c), KEY a (a,b,c)) Engine=InnoDB;
+
+INSERT INTO t1 VALUES (1, 1);
+INSERT INTO t1 SELECT a + 1, b + 1 FROM t1; 
+INSERT INTO t1 SELECT a + 2, b + 2 FROM t1; 
+
+INSERT INTO t2 VALUES (1,1),(1,2),(1,3),(1,4),(1,5),(1,6),(1,7),(1,8);
+INSERT INTO t2 SELECT a + 1, b FROM t2;
+DELETE FROM t2 WHERE a = 1 AND b < 2;
+
+INSERT INTO t3 VALUES (1,1,1),(2,1,2);
+INSERT INTO t3 SELECT a + 2, a + 2, 3 FROM t3;
+INSERT INTO t3 SELECT a + 4, a + 4, 3 FROM t3;
+
+# demonstrate a problem when a must-use-sort table flag
+# (sort_by_table=1) is being neglected.
+SELECT STRAIGHT_JOIN SQL_NO_CACHE t1.b, t1.a FROM t1, t3, t2 WHERE 
+  t3.a = t2.a AND t2.b = t1.a AND t3.b = 1 AND t3.c IN (1, 2) 
+  ORDER BY t1.b LIMIT 2;
+
+# demonstrate the problem described in the bug report
+SELECT STRAIGHT_JOIN SQL_NO_CACHE t1.b, t1.a FROM t1, t3, t2 WHERE 
+  t3.a = t2.a AND t2.b = t1.a AND t3.b = 1 AND t3.c IN (1, 2) 
+  ORDER BY t1.b LIMIT 5;
+DROP TABLE t1, t2, t3;

sql/sql_select.cc

@@ -3845,6 +3845,7 @@ make_join_readinfo(JOIN *join, uint options)
 {
   uint i;
   bool statistics= test(!(join->select_options & SELECT_DESCRIBE));
+  bool ordered_set= 0;
   DBUG_ENTER("make_join_readinfo");
 
   for (i=join->const_tables ; i < join->tables ; i++)
@@ -3854,6 +3855,22 @@ make_join_readinfo(JOIN *join, uint options)
     tab->read_record.table= table;
     tab->read_record.file=table->file;
     tab->next_select=sub_select;		/* normal select */
+
+    /*
+      Determine if the set is already ordered for ORDER BY, so it can 
+      disable join cache because it will change the ordering of the results.
+      Code handles sort table that is at any location (not only first after 
+      the const tables) despite the fact that it's currently prohibited.
+    */
+    if (!ordered_set && 
+        (table == join->sort_by_table &&
+         (!join->order || join->skip_sort_order ||
+          test_if_skip_sort_order(tab, join->order, join->select_limit,
+                                  1))
+        ) ||
+        (join->sort_by_table == (TABLE *) 1 && i != join->const_tables))
+      ordered_set= 1;
+
     switch (tab->type) {
     case JT_SYSTEM:				// Only happens with left join
       table->status=STATUS_NO_RECORD;
@@ -3924,10 +3941,11 @@ make_join_readinfo(JOIN *join, uint options)
     case JT_ALL:
       /*
 	If previous table use cache
+        If the incoming data set is already sorted don't use cache.
       */
       table->status=STATUS_NO_RECORD;
       if (i != join->const_tables && !(options & SELECT_NO_JOIN_CACHE) &&
-	  tab->use_quick != 2 && !tab->on_expr)
+	  tab->use_quick != 2 && !tab->on_expr && !ordered_set)
       {
 	if ((options & SELECT_DESCRIBE) ||
 	    !join_init_cache(join->thd,join->join_tab+join->const_tables,