Commit 3468f4b4 authored by Georgi Kodinov's avatar Georgi Kodinov
Browse files

Bug#37548: result value erronously reported being NULL in certain subqueries 

      
When switching to indexed ORDER BY we must be sure to reset the index read
flag if we are switching from a covering index to non-covering.
parent 12846f41

mysql-test/r/subselect.result

+39 −0
Original line number Diff line number Diff line
@@ -4391,3 +4391,42 @@ SELECT * FROM t1 WHERE _utf8'a' = ANY (SELECT s1 FROM t1); 
s1

a

DROP TABLE t1;

CREATE TABLE t1 (a int, b int, PRIMARY KEY (a), KEY b (b));

INSERT INTO t1 VALUES (1,NULL), (9,NULL);

CREATE TABLE t2 (

a int,

b int,

c int,

d int,

PRIMARY KEY (a),

UNIQUE KEY b (b,c,d),

KEY b_2 (b),

KEY c (c),

KEY d (d)

);

INSERT INTO t2 VALUES 

(43, 2, 11 ,30),

(44, 2, 12 ,30),

(45, 1, 1  ,10000),

(46, 1, 2  ,10000),

(556,1, 32 ,10000);

CREATE TABLE t3 (

a int,

b int,

c int,

PRIMARY KEY (a),

UNIQUE KEY b (b,c),

KEY c (c),

KEY b_2 (b)

);

INSERT INTO t3 VALUES (1,1,1), (2,32,1);

explain 

SELECT t1.a, (SELECT 1 FROM t2 WHERE t2.b=t3.c AND t2.c=t1.a ORDER BY t2.d LIMIT 1) AS incorrect FROM t1, t3 WHERE t3.b=t1.a;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t3	index	b,b_2	b	10	NULL	2	Using index

1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t3.b	1	Using index

2	DEPENDENT SUBQUERY	t2	index	b,b_2,c	d	5	NULL	1	Using where

SELECT t1.a, (SELECT 1 FROM t2 WHERE t2.b=t3.c AND t2.c=t1.a ORDER BY t2.d LIMIT 1) AS incorrect FROM t1, t3 WHERE t3.b=t1.a;

a	incorrect

1	1

DROP TABLE t1,t2,t3;

mysql-test/t/subselect.test

+44 −0
Original line number Diff line number Diff line
@@ -3273,3 +3273,47 @@ INSERT INTO t1 VALUES ('a'); 
SELECT * FROM t1 WHERE _utf8'a' = ANY (SELECT s1 FROM t1);

DROP TABLE t1;



#

# Bug #37548: result value erronously reported being NULL in certain subqueries

#



CREATE TABLE t1 (a int, b int, PRIMARY KEY (a), KEY b (b));



INSERT INTO t1 VALUES (1,NULL), (9,NULL);



CREATE TABLE t2 (

  a int,

  b int,

  c int,

  d int,

  PRIMARY KEY (a),

  UNIQUE KEY b (b,c,d),

  KEY b_2 (b),

  KEY c (c),

  KEY d (d)

);



INSERT INTO t2 VALUES 

  (43, 2, 11 ,30),

  (44, 2, 12 ,30),

  (45, 1, 1  ,10000),

  (46, 1, 2  ,10000),

  (556,1, 32 ,10000);



CREATE TABLE t3 (

  a int,

  b int,

  c int,

  PRIMARY KEY (a),

  UNIQUE KEY b (b,c),

  KEY c (c),

  KEY b_2 (b)

);



INSERT INTO t3 VALUES (1,1,1), (2,32,1);



explain 

SELECT t1.a, (SELECT 1 FROM t2 WHERE t2.b=t3.c AND t2.c=t1.a ORDER BY t2.d LIMIT 1) AS incorrect FROM t1, t3 WHERE t3.b=t1.a;

SELECT t1.a, (SELECT 1 FROM t2 WHERE t2.b=t3.c AND t2.c=t1.a ORDER BY t2.d LIMIT 1) AS incorrect FROM t1, t3 WHERE t3.b=t1.a;



DROP TABLE t1,t2,t3;

sql/sql_select.cc

+10 −0
Original line number Diff line number Diff line
@@ -13155,6 +13155,16 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit, 
            table->key_read=1;

            table->file->extra(HA_EXTRA_KEYREAD);

          }

          else if (table->key_read)

          {

            /*

              Clear the covering key read flags that might have been

              previously set for some key other than the current best_key.

            */

            table->key_read= 0;

            table->file->extra(HA_EXTRA_NO_KEYREAD);

          }









          table->file->ha_index_or_rnd_end();









          if (join->select_options & SELECT_DESCRIBE)









          {