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Bug #31001: ORDER BY DESC in InnoDB not working

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The optimizer sets index traversal in reverse order only if there are 
 used key parts that are not compared to a constant.
However using the primary key as an ORDER BY suffix rendered the check
incomplete : going in reverse order must still be used even if 
all the parts of the secondary key are compared to a constant.

Fixed by relaxing the check and set reverse traversal even when all
the secondary index keyparts are compared to a const.
Also account for the case when all the primary keys are compared to a
constant.


mysql-test/r/innodb_mysql.result:
  Bug #31001: test case
mysql-test/t/innodb_mysql.test:
  Bug #31001: test case
sql/sql_select.cc:
  Bug #31001: 
   - account for the case when all the primary key parts are compared
     to a constant
   - force test_if_skip_sort_order to go backwards over the key even 
     when the number of keyparts used is the same as the number of 
     keyparts equal to a constant. (because of the primary key 
     suffix).
This commit is contained in:
unknown
2007-09-14 17:43:14 +03:00
parent aa5da0fc9e
commit ad496be063
3 changed files with 127 additions and 1 deletions
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23
mysql-test/t/innodb_mysql.test
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@ -937,4 +937,27 @@ SELECT c,b FROM t1 GROUP BY c,b;
DROP TABLE t1;
#
# Bug #31001: ORDER BY DESC in InnoDB not working
#
CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a), INDEX b (b)) ENGINE=InnoDB;
INSERT INTO t1(a,b) VALUES (1,1), (2,2), (3,2);
#The two queries below should produce different results, but they don't.
query_vertical EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a ASC;
SELECT * FROM t1 WHERE b=2 ORDER BY a ASC;
query_vertical EXPLAIN SELECT * FROM t1 WHERE b=2 ORDER BY a DESC;
SELECT * FROM t1 WHERE b=2 ORDER BY a DESC;
query_vertical EXPLAIN SELECT * FROM t1 ORDER BY b ASC, a ASC;
SELECT * FROM t1 ORDER BY b ASC, a ASC;
query_vertical EXPLAIN SELECT * FROM t1 ORDER BY b DESC, a DESC;
SELECT * FROM t1 ORDER BY b DESC, a DESC;
query_vertical EXPLAIN SELECT * FROM t1 ORDER BY b ASC, a DESC;
SELECT * FROM t1 ORDER BY b ASC, a DESC;
query_vertical EXPLAIN SELECT * FROM t1 ORDER BY b DESC, a ASC;
SELECT * FROM t1 ORDER BY b DESC, a ASC;
DROP TABLE t1;
--echo End of 5.0 tests