From 9201bff16b93743aa1a8bfaeff990daf050a2a8d Mon Sep 17 00:00:00 2001
From: Alexey Kopytov <Alexey.Kopytov@Sun.com>
Date: Thu, 25 Feb 2010 18:48:53 +0300
Subject: [PATCH] Bug #50335: Assertion `!(order->used & map)' in eq_ref_table

The problem was in an incorrect debug assertion. The expression
used in the failing assertion states that when finding
references matching ORDER BY expressions, there can be only one
reference to a single table. But that does not make any sense,
all test cases for this bug are valid examples with multiple
identical WHERE expressions referencing the same table which
are also present in the ORDER BY list.

Fixed by removing the failing assertion. We also have to take
care of the 'found' counter so that we count multiple
references only once. We rely on this fact later in
eq_ref_table().

mysql-test/r/join.result:
  Added a test case for bug #50335.
mysql-test/t/join.test:
  Added a test case for bug #50335.
sql/sql_select.cc:
  Removing the assertion in eq_ref_table() as it does not make
  any sense. We also have to take care of the 'found' counter so
  that we count multiple references only once. We rely on this
  fact later in eq_ref_table().
---
 mysql-test/r/join.result | 11 +++++++++++
 mysql-test/t/join.test   | 13 +++++++++++++
 sql/sql_select.cc        |  8 +++++---
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/mysql-test/r/join.result b/mysql-test/r/join.result
index 8691eb27220..102b39c3992 100644
--- a/mysql-test/r/join.result
+++ b/mysql-test/r/join.result
@@ -1145,3 +1145,14 @@ NULL
 NULL
 1
 DROP TABLE t1, t2, mm1;
+#
+# Bug #50335: Assertion `!(order->used & map)' in eq_ref_table
+# 
+CREATE TABLE t1 (a INT NOT NULL, b INT NOT NULL, PRIMARY KEY (a,b));
+INSERT INTO t1 VALUES (0,0), (1,1);
+SELECT * FROM t1 STRAIGHT_JOIN t1 t2 ON t1.a=t2.a AND t1.a=t2.b ORDER BY t2.a, t1.a;
+a	b	a	b
+0	0	0	0
+1	1	1	1
+DROP TABLE t1;
+End of 5.1 tests
diff --git a/mysql-test/t/join.test b/mysql-test/t/join.test
index 645321a3a5e..761121313e5 100644
--- a/mysql-test/t/join.test
+++ b/mysql-test/t/join.test
@@ -816,3 +816,16 @@ CREATE TABLE mm1(a CHAR(9),b INT,KEY(b),KEY(a))
 ENGINE=MERGE  UNION=(t1,t2);
 SELECT t1.a FROM mm1,t1;
 DROP TABLE t1, t2, mm1;
+
+--echo #
+--echo # Bug #50335: Assertion `!(order->used & map)' in eq_ref_table
+--echo # 
+
+CREATE TABLE t1 (a INT NOT NULL, b INT NOT NULL, PRIMARY KEY (a,b));
+INSERT INTO t1 VALUES (0,0), (1,1);
+
+SELECT * FROM t1 STRAIGHT_JOIN t1 t2 ON t1.a=t2.a AND t1.a=t2.b ORDER BY t2.a, t1.a;
+
+DROP TABLE t1;
+
+--echo End of 5.1 tests
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 52f9aae7a0c..b9f59fac4d6 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -7028,9 +7028,11 @@ eq_ref_table(JOIN *join, ORDER *start_order, JOIN_TAB *tab)
       }
       if (order)
       {
-	found++;
-	DBUG_ASSERT(!(order->used & map));
-	order->used|=map;
+        if (!(order->used & map))
+        {
+          found++;
+          order->used|= map;
+        }
 	continue;				// Used in ORDER BY
       }
       if (!only_eq_ref_tables(join,start_order, (*ref_item)->used_tables()))