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Bug#48229: group by performance issue of partitioned table

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Problem was block_size on partitioned tables was not set,
resulting in keys_per_block was not correct which affects
the cost calculation for read time of indexes (including
cost for group min/max).Which resulted in a bad optimizer
decision.

Fixed by setting stats.block_size correctly.
This commit is contained in:
Mattias Jonsson 2010-03-04 12:09:09 +01:00
parent be2a015e12
commit 2d5c6b5bfe
3 changed files with 33 additions and 0 deletions
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14
mysql-test/r/partition_range.result
View File

@ -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));

18
mysql-test/t/partition_range.test
View File

@ -9,6 +9,24 @@
drop table if exists t1, t2;
--enable_warnings
--echo #
--echo # Bug#48229: group by performance issue of partitioned table
--echo #
CREATE TABLE t1 (
a INT,
b INT,
KEY a (a,b)
)
PARTITION BY HASH (a) PARTITIONS 1;
# insert some rows (i.e. so that rows/blocks > 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);
# Before the fix the 'Extra' column showed 'Using index for group-by'
EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100, 3) GROUP BY a;
DROP TABLE t1;
#
# BUG 33429: Succeeds in adding partition when maxvalue on last partition
#

1
sql/ha_partition.cc
View File

@ -5053,6 +5053,7 @@ int ha_partition::info(uint flag)
file= m_file[handler_instance];
file->info(HA_STATUS_CONST);
stats.block_size= file->stats.block_size;
stats.create_time= file->stats.create_time;
ref_length= m_ref_length;
}