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This commit is contained in:
Mattias Jonsson 2010-09-13 16:07:50 +02:00
commit 9d1ed095f5
3 changed files with 55 additions and 0 deletions
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21
mysql-test/r/order_by.result
View file

@ -1617,4 +1617,25 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 2 Using where; Using temporary; Using filesort
1 SIMPLE t2 ALL NULL NULL NULL NULL 10 Using join buffer
DROP TABLE t1, t2;
#
# Bug #50394: Regression in EXPLAIN with index scan, LIMIT, GROUP BY and
# ORDER BY computed col
#
CREATE TABLE t1 ( a INT NOT NULL, b INT NOT NULL, KEY( a, b ) );
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
INSERT INTO t1 SELECT a + 5, b + 5 FROM t1;
CREATE TABLE t2( a INT PRIMARY KEY, b INT );
INSERT INTO t2 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
INSERT INTO t2 SELECT a + 5, b + 5 FROM t2;
EXPLAIN
SELECT count(*) AS c, t1.a
FROM t1 JOIN t2 ON t1.b = t2.a
WHERE t2.b = 1
GROUP BY t1.a
ORDER by c
LIMIT 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 8 NULL 10 Using index; Using temporary; Using filesort
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.b 1 Using where
DROP TABLE t1, t2;
End of 5.1 tests

25
mysql-test/t/order_by.test
View file

@ -1467,4 +1467,29 @@ SELECT * FROM t1 FORCE INDEX FOR JOIN (a), t2 WHERE t1.a < 2 ORDER BY t1.a;
DROP TABLE t1, t2;
--echo #
--echo # Bug #50394: Regression in EXPLAIN with index scan, LIMIT, GROUP BY and
--echo # ORDER BY computed col
--echo #
CREATE TABLE t1 ( a INT NOT NULL, b INT NOT NULL, KEY( a, b ) );
INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
INSERT INTO t1 SELECT a + 5, b + 5 FROM t1;
CREATE TABLE t2( a INT PRIMARY KEY, b INT );
INSERT INTO t2 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
INSERT INTO t2 SELECT a + 5, b + 5 FROM t2;
EXPLAIN
SELECT count(*) AS c, t1.a
FROM t1 JOIN t2 ON t1.b = t2.a
WHERE t2.b = 1
GROUP BY t1.a
ORDER by c
LIMIT 2;
DROP TABLE t1, t2;
--echo End of 5.1 tests

9
sql/sql_select.cc
View file

@ -1486,6 +1486,15 @@ JOIN::optimize()
}
if (order)
{
/*
Do we need a temporary table due to the ORDER BY not being equal to
the GROUP BY? The call to test_if_skip_sort_order above tests for the
GROUP BY clause only and hence is not valid in this case. So the
estimated number of rows to be read from the first table is not valid.
We clear it here so that it doesn't show up in EXPLAIN.
*/
if (need_tmp && (select_options & SELECT_DESCRIBE) != 0)
join_tab[const_tables].limit= 0;
/*
Force using of tmp table if sorting by a SP or UDF function due to
their expensive and probably non-deterministic nature.