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Merge of fix for Bug#54444.

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This commit is contained in:
Martin Hansson
2010-08-11 17:55:07 +02:00
parent afd775d9e1 41cfa3e769
commit 2c47236bef
4 changed files with 85 additions and 85 deletions
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44
mysql-test/r/partition_range.result
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@ -938,3 +938,47 @@ select sum(count) from t2 ch where ch.defid in (50,52) and ch.day between 200703
sum(count)
579
drop table t1, t2;
#
# Bug#50939: Loose Index Scan unduly relies on engine to remember range
# endpoints
#
CREATE TABLE t1 (
a INT,
b INT,
KEY ( a, b )
) PARTITION BY HASH (a) PARTITIONS 1;
CREATE TABLE t2 (
a INT,
b INT,
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;
INSERT INTO t1 SELECT a + 10, b + 10 FROM t1;
INSERT INTO t1 SELECT a + 20, b + 20 FROM t1;
INSERT INTO t1 SELECT a + 40, b + 40 FROM t1;
INSERT INTO t2 SELECT * FROM t1;
# plans should be identical
EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10,100) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 1 Using where; Using index for group-by
EXPLAIN SELECT a, MAX(b) FROM t2 WHERE a IN (10,100) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range a a 5 NULL 2 Using where; Using index for group-by
FLUSH status;
SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100) GROUP BY a;
a MAX(b)
10 10
# Should be no more than 4 reads.
SHOW status LIKE 'handler_read_key';
Variable_name Value
Handler_read_key 4
FLUSH status;
SELECT a, MAX(b) FROM t2 WHERE a IN (10, 100) GROUP BY a;
a MAX(b)
10 10
# Should be no more than 4 reads.
SHOW status LIKE 'handler_read_key';
Variable_name Value
Handler_read_key 4
DROP TABLE t1, t2;