Fix for bug #30666: Incorrect order when using range conditions on 2

tables or more

The problem was that the optimizer used the join buffer in cases when
the result set is ordered by filesort. This resulted in the ORDER BY
clause being ignored, and the records being returned in the order
determined by the order of matching records in the last table in join.

Fixed by relaxing the condition in make_join_readinfo() to take
filesort-ordered result sets into account, not only index-ordered ones.


mysql-test/r/select.result:
  Added a test case for bug #30666.
mysql-test/t/select.test:
  Added a test case for bug #30666.
sql/sql_select.cc:
  Relaxed the condition to determine when the join buffer usage must be
  disabled. The condition is now true for cases when the result set is
  ordered by filesort, that is when 'join->order &&
  !join->skip_sort_order' is true.

1 files changed, 36 insertions, 0 deletions

diff --git a/mysql-test/t/select.test b/mysql-test/t/select.test
index 5c30a17e08e..7fe866e6495 100644
--- a/mysql-test/t/select.test
+++ b/mysql-test/t/select.test
@@ -3484,4 +3484,40 @@ DROP VIEW v1, v2, v3;
 
 --enable_ps_protocol
 
+#
+# Bug #30666: Incorrect order when using range conditions on 2 tables or more
+#
+
+CREATE TABLE t1 (c11 INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY);
+CREATE TABLE t2 (c21 INT UNSIGNED NOT NULL, 
+                 c22 INT DEFAULT NULL, 
+                 KEY(c21, c22));
+CREATE TABLE t3 (c31 INT UNSIGNED NOT NULL DEFAULT 0, 
+                 c32 INT DEFAULT NULL, 
+                 c33 INT NOT NULL, 
+                 c34 INT UNSIGNED DEFAULT 0,
+                 KEY (c33, c34, c32));
+
+INSERT INTO t1 values (),(),(),(),();
+INSERT INTO t2 SELECT a.c11, b.c11 FROM t1 a, t1 b;
+INSERT INTO t3 VALUES (1, 1, 1, 0), 
+                      (2, 2, 0, 0), 
+                      (3, 3, 1, 0), 
+                      (4, 4, 0, 0), 
+                      (5, 5, 1, 0);
+
+# Show that ORDER BY produces the correct results order
+SELECT c32 FROM t1, t2, t3 WHERE t1.c11 IN (1, 3, 5) AND 
+                                 t3.c31 = t1.c11 AND t2.c21 = t1.c11 AND 
+                                 t3.c33 = 1 AND t2.c22 in (1, 3) 
+                           ORDER BY c32; 
+
+# Show that ORDER BY DESC produces the correct results order
+SELECT c32 FROM t1, t2, t3 WHERE t1.c11 IN (1, 3, 5) AND 
+                                 t3.c31 = t1.c11 AND t2.c21 = t1.c11 AND 
+                                 t3.c33 = 1 AND t2.c22 in (1, 3) 
+                           ORDER BY c32 DESC; 
+
+DROP TABLE t1, t2, t3;
+
 --echo End of 5.0 tests