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Fixed bug#35844.

Browse Source 
The function test_if_skip_sort_order ignored any covering index used for ref
access of a table in a query with ORDER BY if this index was incompatible 
with the ORDER BY list and there was another covering index compatible with
this list. 
As a result sub-optimal execution plans were chosen for some queries with
ORDER BY clause. 


mysql-test/r/distinct.result:
  Adjusted results after the fix for bug#35844.
mysql-test/r/order_by.result:
  Added a test case for bug#35844.
mysql-test/t/order_by.test:
  Added a test case for bug#35844.
This commit is contained in:
unknown
2008-04-22 21:49:39 -07:00
parent c481f6b3cf
commit 61f6c60274
4 changed files with 65 additions and 2 deletions
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26
mysql-test/r/order_by.result
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@ -1458,3 +1458,29 @@ ORDER BY t2.c LIMIT 1;
d
52.5
DROP TABLE t1,t2,t3;
CREATE TABLE t1 (
id1 INT NULL,
id2 INT NOT NULL,
junk INT NOT NULL,
PRIMARY KEY (id1, id2, junk),
INDEX id2_j_id1 (id2, junk, id1)
);
INSERT INTO t1 VALUES (1, 1, 1), (2, 1, 2), (3, 1, 3), (4, 1, 4);
INSERT INTO t1 VALUES (5, 2, 1), (6, 2, 2), (7, 2, 3), (8, 2, 4);
INSERT INTO t1 VALUES (9, 3, 1), (10, 3, 2), (11, 3, 3), (12, 3, 4);
INSERT INTO t1 VALUES (13, 4, 1), (14, 4, 2), (15, 4, 3), (16, 4, 4);
INSERT INTO t1 VALUES (17, 5, 1), (18, 5, 2), (19, 5, 3), (20, 5, 4);
INSERT INTO t1 VALUES (21, 6, 1), (22, 6, 2), (23, 6, 3), (24, 6, 4);
INSERT INTO t1 VALUES (25, 7, 1), (26, 7, 2), (27, 7, 3), (28, 7, 4);
INSERT INTO t1 VALUES (29, 8, 1), (30, 8, 2), (31, 8, 3), (32, 8, 4);
INSERT INTO t1 VALUES (33, 9, 1), (34, 9, 2), (35, 9, 3), (36, 9, 4);
EXPLAIN SELECT id1 FROM t1 WHERE id2 = 4 ORDER BY id1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref id2_j_id1 id2_j_id1 4 const 4 Using where; Using index; Using filesort
SELECT id1 FROM t1 WHERE id2 = 4 ORDER BY id1;
id1
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DROP TABLE t1;