mirror of
https://github.com/MariaDB/server.git
synced 2025-02-09 23:24:11 +01:00
45 lines
1.3 KiB
Text
45 lines
1.3 KiB
Text
drop table if exists 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 2 Using where; Using index
|
|
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
|
|
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 2
|
|
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 2
|
|
DROP TABLE t1, t2;
|