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This commit is contained in:
Mattias Jonsson
2010-03-11 14:18:44 +01:00
3 changed files with 33 additions and 0 deletions

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@@ -1,4 +1,18 @@
drop table if exists t1, t2;
#
# Bug#48229: group by performance issue of partitioned table
#
CREATE TABLE t1 (
a INT,
b INT,
KEY a (a,b)
)
PARTITION BY HASH (a) PARTITIONS 1;
INSERT INTO t1 VALUES (0, 580092), (3, 894076), (4, 805483), (4, 913540), (6, 611137), (8, 171602), (9, 599495), (9, 746305), (10, 272829), (10, 847519), (12, 258869), (12, 929028), (13, 288970), (15, 20971), (15, 105839), (16, 788272), (17, 76914), (18, 827274), (19, 802258), (20, 123677), (20, 587729), (22, 701449), (25, 31565), (25, 230782), (25, 442887), (25, 733139), (25, 851020);
EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100, 3) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 4 Using where; Using index
DROP TABLE t1;
create table t1 (a int)
partition by range (a)
( partition p0 values less than (maxvalue));