Why mariadb partitioning doesn't give me better performance? - mysql

Question

Greeting.
Let me show my table scheme first:
CREATE TABLE `log_table` (
`rid` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`dataId` int(10) unsigned NOT NULL DEFAULT '0',
`memberId` int(10) unsigned NOT NULL DEFAULT '0',
`clientId` int(10) unsigned NOT NULL DEFAULT '0',
`qty` int(11) NOT NULL DEFAULT '0',
`timestamp` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
`typeA` tinyint(2) DEFAULT NULL,
`typeB` int(11) DEFAULT '0',
PRIMARY KEY (`rid`,`timestamp`),
KEY `idx_report1` (`timestamp`,`memberId`,`dataId`),
KEY `idx_report2` (`memberId`,`timestamp`),
KEY `idx_report3` (`dataId`,`timestamp`,`rid`),
KEY `idx_report4` (`timestamp`,`typeB`,`typeA`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
PARTITION BY RANGE (year(`timestamp`))
(PARTITION p2014 VALUES LESS THAN (2015),
PARTITION p2015 VALUES LESS THAN (2016)
);
I'm using MariaDB 5.5 and this table contains 25 million records, so I decided to make partitions in the table for preventing performance issue may occur in the near future.
You may see it's time serial, log data, and having 4 views. For example, one of the views uses following query:
select typeB, typeA, count(*) as number from log_table where timestamp between '2015-1-1' and '2015-2-1' group by typeB, typeA;
AFAIK, this query loads the data from p2015 only by partition pruning. But I saw there is not much difference between original table and partition-version in query execution time. (avg 1.94 sec vs 1.95 sec)
Hm, I thought it's might influenced by number of rows in each partition. then how about smaller size of partition? to_days()?
PARTITION BY RANGE (to_days(`timestamp`))
(
...
PARTITION p_2015_01 VALUES LESS THAN (to_days('2015-2-1')),
PARTITION p_2015_02 VALUES LESS THAN (to_days('2015-3-1'))
...
)
Well, there's no effect. Could you let me know what's my missing piece?
EDIT: sorry for my error in the query.. btw, EXPLAIN PARTITION doesn't help me.
and result of explain both tables are :
// original
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+
| 1 | SIMPLE | org_table | range | idx_report1,idx_report4 | idx_report4 | 8 | NULL | 8828000 | Using where; Using index; Using temporary; Using filesort |
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+
//partition
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+
| 1 | SIMPLE | log_table | range | idx_report1,idx_report4 | idx_report4 | 8 | NULL | 7902646 | Using where; Using index; Using temporary; Using filesort |
+------+-------------+-----------+-------+-------------------------+-------------+---------+------+---------+-----------------------------------------------------------+

Answer 1

PARTITIONing does not help performance nearly as often as users think it will.
KEY `idx_report4` (`timestamp`,`typeB`,`typeA`)
without partitioning is optimal for the SELECT you provided. PARTITIONing will not speed it up any.
Since BETWEEN is "inclusive" where timestamp between '2015-1-1' and '2015-2-1' actually hits two partitions. Use EXPLAIN PARTITIONS SELECT ... to see that.
BY RANGE (TO_DAYS(...)) is probably better than BY RANGE (YEAR(...)), but still not useful for the given query.
Here is my discussion of the only 4 use cases where PARTITIONing helps performance: http://mysql.rjweb.org/doc.php/partitionmaint
If this type of query is important, consider "Summary Tables" as a way of greatly speeding up the application: http://mysql.rjweb.org/doc.php/datawarehouse and http://mysql.rjweb.org/doc.php/summarytables