From abc123391f5a22e18c8e260541dbdbde1375e8b5 Mon Sep 17 00:00:00 2001
From: Igor Babaev <igor@askmonty.org>
Date: Fri, 12 Jan 2018 00:14:40 -0800
Subject: [PATCH] Fixed mdev-6706 Wrong result (missing rows) with joins, SQ,
 ORDER BY, semijoin=on

A bug in get_sort_by_table() could mislead the function
setup_semijoin_dups_elimination(). As a result the optimizer
could produce invalid execution plans for queries with ORDER BY
and subquery predicates that could be converted to semi-joins.
---
 mysql-test/r/order_by.result | 46 ++++++++++++++++++++++++++++++++++++
 mysql-test/t/order_by.test   | 38 +++++++++++++++++++++++++++++
 sql/sql_select.cc            |  1 +
 3 files changed, 85 insertions(+)

diff --git a/mysql-test/r/order_by.result b/mysql-test/r/order_by.result
index 94a38ca7827..d3f5cd89eee 100644
--- a/mysql-test/r/order_by.result
+++ b/mysql-test/r/order_by.result
@@ -2061,4 +2061,50 @@ ORDER BY NULL, @a0 := 3, @a1 := 3, @a2 := 3, @a3 := 3, @a4 := 3,
 1
 1
 2
+#
+# mdev-6706: semi-join with duplicate weedout + ORDER BY
+#
+CREATE TABLE t1 (f1 VARCHAR(3)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('foo');
+CREATE TABLE t2 (f2 VARCHAR(3)) ENGINE=MyISAM;
+INSERT INTO t2 VALUES ('bar'),('baz');
+CREATE TABLE t3
+(i3_key INT, f3_key VARCHAR(3), f3 VARCHAR(3), KEY(f3_key,i3_key))
+ENGINE=MyISAM;
+INSERT INTO t3 VALUES (0,'qux','qux'),(8,'bar','bar');
+SELECT CONCAT( f1, f2 ) AS field FROM t1, t2
+WHERE f1 = ANY ( SELECT f1
+FROM t1
+LEFT JOIN ( t3 AS t3a, t3 AS t3b )
+ON ( t3b.f3_key = t3a.f3 )
+WHERE t3a.f3 < f1 OR t3b.f3 != f1 );
+field
+foobar
+foobaz
+SELECT CONCAT( f1, f2 ) AS field FROM t1, t2
+WHERE f1 = ANY ( SELECT f1
+FROM t1
+LEFT JOIN ( t3 AS t3a, t3 AS t3b )
+ON ( t3b.f3_key = t3a.f3 )
+WHERE t3a.f3 < f1 OR t3b.f3 != f1 )
+ORDER BY field;
+field
+foobar
+foobaz
+EXPLAIN EXTENDED SELECT CONCAT( f1, f2 ) AS field FROM t1, t2
+WHERE f1 = ANY ( SELECT f1
+FROM t1
+LEFT JOIN ( t3 AS t3a, t3 AS t3b )
+ON ( t3b.f3_key = t3a.f3 )
+WHERE t3a.f3 < f1 OR t3b.f3 != f1 )
+ORDER BY field;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	100.00	Using temporary; Using filesort
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	100.00	
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	PRIMARY	t3a	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Start temporary
+1	PRIMARY	t3b	ref	f3_key	f3_key	6	test.t3a.f3	1	100.00	Using where; End temporary
+Warnings:
+Note	1003	select concat('foo',`test`.`t2`.`f2`) AS `field` from `test`.`t2` semi join ((`test`.`t3` `t3a` join `test`.`t3` `t3b`)) where ((`test`.`t3a`.`f3` < 'foo') or (`test`.`t3b`.`f3` <> 'foo')) order by concat('foo',`test`.`t2`.`f2`)
+DROP TABLE t1,t2,t3;
 End of 5.5 tests
diff --git a/mysql-test/t/order_by.test b/mysql-test/t/order_by.test
index c96d5c2996a..398f9cb7dd2 100644
--- a/mysql-test/t/order_by.test
+++ b/mysql-test/t/order_by.test
@@ -1756,6 +1756,44 @@ UNION
     ORDER BY NULL, @a0 := 3, @a1 := 3, @a2 := 3, @a3 := 3, @a4 := 3,
              @a5 := 3, @a6 := 3, @a7 := 3, @a8 := 3, @a9 := 3, @a10 := 3 );
 
+
+--echo #
+--echo # mdev-6706: semi-join with duplicate weedout + ORDER BY
+--echo #
+
+CREATE TABLE t1 (f1 VARCHAR(3)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('foo');
+
+CREATE TABLE t2 (f2 VARCHAR(3)) ENGINE=MyISAM;
+INSERT INTO t2 VALUES ('bar'),('baz');
+
+CREATE TABLE t3
+(i3_key INT, f3_key VARCHAR(3), f3 VARCHAR(3), KEY(f3_key,i3_key))
+ ENGINE=MyISAM;
+INSERT INTO t3 VALUES (0,'qux','qux'),(8,'bar','bar');
+
+let $q1=
+SELECT CONCAT( f1, f2 ) AS field FROM t1, t2
+WHERE f1 = ANY ( SELECT f1
+                 FROM t1
+                 LEFT JOIN ( t3 AS t3a, t3 AS t3b )
+                 ON ( t3b.f3_key = t3a.f3 )
+                 WHERE t3a.f3 < f1 OR t3b.f3 != f1 );
+let $q2=
+SELECT CONCAT( f1, f2 ) AS field FROM t1, t2
+WHERE f1 = ANY ( SELECT f1
+                 FROM t1
+                 LEFT JOIN ( t3 AS t3a, t3 AS t3b )
+                 ON ( t3b.f3_key = t3a.f3 )
+                 WHERE t3a.f3 < f1 OR t3b.f3 != f1 )
+ORDER BY field;
+
+eval $q1;
+eval $q2;
+eval EXPLAIN EXTENDED $q2;
+
+DROP TABLE t1,t2,t3;
+
 --echo End of 5.5 tests
 
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index c7f547edbc0..5a7fa4d2c6f 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -21159,6 +21159,7 @@ get_sort_by_table(ORDER *a,ORDER *b, List<TABLE_LIST> &tables,
   if (!map || (map & (RAND_TABLE_BIT | OUTER_REF_TABLE_BIT)))
     DBUG_RETURN(0);
 
+  map&= ~const_tables;
   while ((table= ti++) && !(map & table->table->map)) ;
   if (map != table->table->map)
     DBUG_RETURN(0);				// More than one table