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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.

mysql-test/r/partition_range.result:
  Bug#48229: group by performance issue of partitioned table
  
  Added result
mysql-test/t/partition_range.test:
  Bug#48229: group by performance issue of partitioned table
  
  Added test
sql/ha_partition.cc:
  Bug#48229: group by performance issue of partitioned table
  
  Added missing assignment of stats.block_size.
This commit is contained in:
Mattias Jonsson
2010-03-04 12:09:09 +01:00
parent ae3e094191
commit e46d120e8e
3 changed files with 33 additions and 0 deletions
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18
mysql-test/t/partition_range.test
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@ -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
#