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sql_select.cc:

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Fixed bug #12144.
  Added an optimization that avoids key access with null keys for the 'ref'
  method when used in outer joins. The regilar optimization with adding
  IS NOT NULL expressions is not applied for outer join on expressions as
  the predicates of these expressions are not pushed down in 4.1.
null_key.result, null_key.test:
  Added a test case for bug #12144.


mysql-test/t/null_key.test:
  Added a test case for bug #12144.
mysql-test/r/null_key.result:
  Added a test case for bug #12144.
sql/sql_select.cc:
  Fixed bug #12144.
  Added an optimization that avoids key access with null keys for the 'ref'
  method when used in outer joins. The regilar optimization with adding
  IS NOT NULL expressions is not applied for outer join on expressions as
  the predicates of these expressions are not pushed down in 4.1.
This commit is contained in:
unknown
2005-07-28 13:31:15 -07:00
parent bdc0c67195
commit 74e523d259
3 changed files with 65 additions and 1 deletions
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31
mysql-test/r/null_key.result
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@ -364,3 +364,34 @@ select * from t1;
id id2
1 1
drop table t1;
CREATE TABLE t1 (a int);
CREATE TABLE t2 (a int, b int, INDEX idx(a));
CREATE TABLE t3 (b int, INDEX idx(b));
INSERT INTO t1 VALUES (1), (2), (3), (4);
INSERT INTO t2 VALUES (1, 1), (3, 1);
INSERT INTO t3 VALUES
(NULL), (NULL), (NULL), (NULL), (NULL),
(NULL), (NULL), (NULL), (NULL), (NULL),
(2);
ANALYZE table t1, t2, t3;
Table Op Msg_type Msg_text
test.t1 analyze status OK
test.t2 analyze status OK
test.t3 analyze status OK
EXPLAIN SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
LEFT JOIN t3 ON t2.b=t3.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4
1 SIMPLE t2 ref idx idx 5 test.t1.a 1
1 SIMPLE t3 ref idx idx 5 test.t2.b 1 Using index
SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
LEFT JOIN t3 ON t2.b=t3.b;
a a b b
1 1 1 NULL
2 NULL NULL NULL
3 3 1 NULL
4 NULL NULL NULL
SELECT FOUND_ROWS();
FOUND_ROWS()
4
DROP TABLE t1,t2,t3;