MySQL table partitioning on timestamp - mysql

Question

I have partitioned a table (because of an out of memory error - table got too big). I have partitioned it on a timestamp column as shown below:
CREATE TABLE test (
fname VARCHAR(50) NOT NULL,
lname VARCHAR(50) NOT NULL,
dob timestamp NOT NULL
)
PARTITION BY RANGE( unix_timestamp(dob) ) (
PARTITION p2012 VALUES LESS THAN (unix_timestamp('2013-01-01 00:00:00')),
PARTITION p2013 VALUES LESS THAN (unix_timestamp('2014-01-01 00:00:00')),
PARTITION pNew VALUES LESS THAN MAXVALUE
);
I was hoping that the process of partitioning would also help in speeding up a couple of my queries whihc take a few hours to run; however, this type of partitioning doesn't seem to kick in and all partitions are still being used and scanned through for the queries. I have tried, and failed, with a couple more approaches:
1) Tried to use different range for the partitioning
CREATE TABLE t2 (
fname VARCHAR(50) NOT NULL,
lname VARCHAR(50) NOT NULL,
region_code TINYINT UNSIGNED NOT NULL,
dob timestamp NOT NULL
)
PARTITION BY RANGE( YEAR(dob) ) (
PARTITION p2012 VALUES LESS THAN (2013),
PARTITION p2013 VALUES LESS THAN (2014),
PARTITION pNew VALUES LESS THAN MAXVALUE
);
However, that results in an error: Error Code: 1486. Constant, random or timezone-dependent expressions in (sub)partitioning function are not allowed
2) Gave up on changing partitioning to be recognized by the query optimizer, and as suggested in MySQL's Doc - 18.5 Partition Selection tried specifying which partitions to use in the select statement instead:
select * from t2 partition (p2012)
But, that returns a syntax error Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(p2012) LIMIT 0, 1000' at line 1
Does anybody have any suggestions what else I could try to utilize table partitioning to optimize the queries?

Answer 1

You can use UNIX_TIMESTAMP() function. Example from MySQL docs:
CREATE TABLE quarterly_report_status (
report_id INT NOT NULL,
report_status VARCHAR(20) NOT NULL,
report_updated TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)
PARTITION BY RANGE ( UNIX_TIMESTAMP(report_updated) ) (
PARTITION p0 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-01-01 00:00:00') ),
PARTITION p1 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-04-01 00:00:00') ),
PARTITION p2 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-07-01 00:00:00') ),
PARTITION p3 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-10-01 00:00:00') ),
PARTITION p4 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-01-01 00:00:00') ),
PARTITION p5 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-04-01 00:00:00') ),
PARTITION p6 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-07-01 00:00:00') ),
PARTITION p7 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-10-01 00:00:00') ),
PARTITION p8 VALUES LESS THAN ( UNIX_TIMESTAMP('2010-01-01 00:00:00') ),
PARTITION p9 VALUES LESS THAN (MAXVALUE)
);
You can find it in:
https://dev.mysql.com/doc/refman/5.7/en/partitioning-range.html.

Answer 2

You can do this if you use DATE or DATETIME instead of TIMESTAMP as the data type.
CREATE TABLE t2 (
fname VARCHAR(50) NOT NULL,
lname VARCHAR(50) NOT NULL,
region_code TINYINT UNSIGNED NOT NULL,
dob DATETIME NOT NULL
)
PARTITION BY RANGE( YEAR(dob) ) (
PARTITION p2012 VALUES LESS THAN (2013),
PARTITION p2013 VALUES LESS THAN (2014),
PARTITION pNew VALUES LESS THAN MAXVALUE
);
Using the partition-selection hint is only supported in MySQL 5.6 and later.
See http://dev.mysql.com/doc/refman/5.6/en/partitioning-selection.html
Note that the page of the manual is only for MySQL 5.6. If you try to click on MySQL 5.5 documentation link, it redirects you back to 5.6.

Answer 3

The wrong is that, This field dob is not unique key!
you can use this command:
CREATE TABLE t2 (
fname VARCHAR(50) NOT NULL,
lname VARCHAR(50) NOT NULL,
region_code TINYINT UNSIGNED NOT NULL,
dob timestamp NOT NULL,
unique 'dob' (dob)
)
or the table is exist:
alter table t2 add UNIQUE(dob)
You can try it!