#At file:///data0/martin/bzr/bug53859/5.1bt/ based on revid:sergey.glukhov@stripped
3387 Martin Hansson 2010-05-28
Bug#53859: Valgrind: opt_sum_query(TABLE_LIST*, List<Item>&,
Item*) at opt_sum.cc:305
Queries where MIN and MAX functions are applied to indexed
columns are optimized to read directly from the index if all
key parts of the index preceding the aggregated key part are
bound to constants by the WHERE clause. A prefix length is
also produced. If the aggregated column itself is bound to a
constant, however, it is also included in the prefix. The
function that was performing the read missed this detail and
tried to read outside the key buffer.
Fixed by simply reading the last key part's position in the
key buffer if the prefix length equals the entire buffer
length.
modified:
mysql-test/r/func_group.result
mysql-test/t/func_group.test
sql/opt_sum.cc
=== modified file 'mysql-test/r/func_group.result'
--- a/mysql-test/r/func_group.result 2009-11-24 15:26:13 +0000
+++ b/mysql-test/r/func_group.result 2010-05-28 07:42:14 +0000
@@ -1713,4 +1713,18 @@ f1 f2 f3 f4 f1 = f2
NULL NULL NULL NULL NULL
drop table t1;
#
+#
+# Bug#53859: Valgrind: opt_sum_query(TABLE_LIST*, List<Item>&, Item*) at
+# opt_sum.cc:305
+#
+CREATE TABLE t1 ( a INT, b INT, KEY (b) );
+INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3);
+# Should not give valgrid warnings.
+SELECT MIN( t1a.b ) AS field1
+FROM t1 t1a LEFT JOIN t1 t1b USING( a )
+WHERE t1a.b > 1 AND t1a.b IS NULL
+ORDER BY field1;
+field1
+NULL
+DROP TABLE t1;
End of 5.1 tests
=== modified file 'mysql-test/t/func_group.test'
--- a/mysql-test/t/func_group.test 2009-11-24 15:26:13 +0000
+++ b/mysql-test/t/func_group.test 2010-05-28 07:42:14 +0000
@@ -1083,5 +1083,20 @@ from t1 a, t1 b;
select *, f1 = f2 from t1;
drop table t1;
--echo #
+--echo #
+--echo # Bug#53859: Valgrind: opt_sum_query(TABLE_LIST*, List<Item>&, Item*) at
+--echo # opt_sum.cc:305
+--echo #
+CREATE TABLE t1 ( a INT, b INT, KEY (b) );
+INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3);
+
+--echo # Should not give valgrid warnings.
+SELECT MIN( t1a.b ) AS field1
+FROM t1 t1a LEFT JOIN t1 t1b USING( a )
+WHERE t1a.b > 1 AND t1a.b IS NULL
+ORDER BY field1;
+
+DROP TABLE t1;
+
--echo End of 5.1 tests
=== modified file 'sql/opt_sum.cc'
--- a/sql/opt_sum.cc 2010-05-12 16:10:33 +0000
+++ b/sql/opt_sum.cc 2010-05-28 07:42:14 +0000
@@ -126,7 +126,18 @@ static int get_index_min_value(TABLE *ta
key. If read fails, and we're looking for a MIN() value for a
nullable column, test if there is an exact match for the key.
*/
- if (!(range_fl & NEAR_MIN))
+ if (prefix_len == ref->key_length)
+ /*
+ In the special case when the argument to the MIN function is also
+ bound to a constant, i.e. SELECT MIN(a) ... WHERE a = <constant>, the
+ prefix is the entire ref key and all we need to do is try to read
+ once using that key.
+ */
+ error= table->file->index_read_map(table->record[0],
+ ref->key_buff,
+ make_prev_keypart_map(ref->key_parts),
+ HA_READ_KEY_EXACT);
+ else if (!(range_fl & NEAR_MIN))
/*
Closed interval: Either The MIN argument is non-nullable, or
we have a >= predicate for the MIN argument.
Attachment: [text/bzr-bundle] bzr/martin.hansson@sun.com-20100528074214-1a9vppkc5k3cgp1e.bundle
