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

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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.
This commit is contained in:
Georgi Kodinov
2008-08-27 18:19:22 +03:00
parent 12846f416e
commit 3468f4b4b3
3 changed files with 93 additions and 0 deletions
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39
mysql-test/r/subselect.result
View File

@@ -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;

44
mysql-test/t/subselect.test
View File

@@ -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;

10
sql/sql_select.cc
View File

@@ -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)
{