This blog was originally published in July 2017 and was updated in August 2023.

It’s a pretty common question around here, so let’s see what we can do about that.

So, What is MySQL Partitioning?

Partitioning is a way in which a database (MySQL in this case) splits its actual data down into separate tables but still gets treated as a single table by the SQL layer.

When partitioning in MySQL, it’s a good idea to find a natural partition key. You want to ensure that table lookups go to the correct partition or group of partitions. This means that all SELECT, UPDATE, and DELETE should include that column in the WHERE clause. Otherwise, the storage engine does a scatter-gather and queries ALL partitions in a UNION that is not concurrent.

Generally, you must add the partition key into the primary key along …

Space constraint has been an endless and painstaking process for many of us, especially in systems that have a high number of transactions and data growth exceeding hundreds of GBs in a matter of days. In this blog, I will share a solution to remove this space and remove rows from tables in a few seconds regardless of the size of a table without causing any additional load on the database using table partitions.

The first approach that comes to anyone’s mind for deleting the row is using a DELETE query in SQL. Suppose, one wants to delete rows from a table that are older than one year—the query for such operations would be like this:

DELETE FROM salaries WHERE from_date <DATE_SUB(NOW(),INTERVAL 1 YEAR);

The above query is pretty straightforward but there are a few caveats:

• Server business will grow exponentially and could impact the usual traffic on the server.
• To speed up the above query …

In this blog post we’ll look at how to move a MySQL partition from one table to another, for MySQL versions before 5.7.

Up to version 5.7, MySQL had a limitation that made it impossible to directly exchange partitions between partitioned tables. Now and then, we get questions about how to import an .ibd for use as a partition in a table, as well as how to exchange partitions with another partitioned table. Below is step-by-step instructions on how to move a partition from one table to another.

In this example, one of our customers had two tables with the following structures:

CREATE TABLE live_tbl (
some_id bigint(20) NOT NULL DEFAULT '0',
summary_date date NOT NULL,
PRIMARY KEY (some_id,summary_date)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
/*!50500 PARTITION BY RANGE …

So this is just a simple example of how to set up a PARTITION and a SUBPARTITION in MySQL. The concept here is that you have data in a table with numerous values in a datetime field. You might have data that is spread across numerous years  (most likely you do). So one way to partition this data is to sort it by year but then also sort it by month within that yearly partition.

Below is an example that you can use for consideration.

Consider the test table. Your table with have many more fields of course.

CREATE TABLE `t1` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `date_time` datetime DEFAULT NOW(),
  PRIMARY KEY (`id`)
) ENGINE=InnoDB;


First I will populate the test table with random values for the  date_time field.

delimiter //
CREATE PROCEDURE populate_t1( IN rowsofdata INT )
…

I checked some updates to Shard-Query into SVN. Partitioning support has been extended for MySQL 5.6+ to ALL partitioning types.

This includes all previously unsupported types including RANGE LIST/COLUMNS partitioned tables that are partitioned over more than one column, and HASH/KEY/LINEAR variants as well. Shard-Query now exclusively uses the PARTITION hint for partition elimination instead of WHERE clauses in MySQL 5.6. For 5.5 and previous versions, support remains limited to LIST,RANGE, and LIST/RANGE COLUMNS over a single column.

The old mysql interface DAL has been replaced completely by the PDO DAL.

There is no major difference for end users except that you have to check that the return of the query() method is an object with the is_object() function instead of checking that it is a resource with the is_resource() function. I updated bin/run_query, which is the example application.

I …

I have worked as an architect in the MySQL/NDB world for more than 20 years and I am still working at Oracle and I like it here. Given all the FUD spread about MySQL I thought it might be a good idea to spread the word about all the great things we're doing to MySQL at Oracle.

#1 We are working on improving modularity in MySQL code base
In the early days of MySQL the MySQL development had serious issues with its development model. It was a model designed for a small code base. I used to work at Ericsson which is developing telecom switches that have systems with tens of millions lines of code. Such large systems require modularity. The Ericsson switches was developed with modularity built into the programming language already since the 70's. Even with this modularity a second level of modularity was required. The learnings from this reengineering project that span over more than a decade has given me valuable insights …

LVM (Logical Volume Management) is a very important tool to have in the toolkit of a MySQL DBA. It allows you to create and extend logical volumes on the fly. This allows me to, say, add another disk and extend a partition effortlessly. The other very important feature is the ability to take snapshots, that you can then use for backups. All in all its a must have tool. Hence, this guide will allow you to understand various terminologies associated with LVM, together with setting up LVM volumes and in a later part will also show you how to extend...

At Kscope this year, I attended a half day in-depth session entitled Data Warehousing Performance Best Practices, given by Maria Colgan of Oracle. My impression, which was confirmed by folks in the Oracle world, is that she knows her way around the Oracle optimizer.

See part 1 for the introduction and talking about power and hardware. This part will go over the 2nd “P”, partitioning. Learning about Oracle’s partitioning has gotten me more interested in how MySQL’s partitioning works, and I do hope that MySQL partitioning will develop to the level that Oracle partitioning does, because Oracle’s partitioning looks very nice (then again, that’s why it costs so much I guess).

Partition – …

One common question I get is how to use partitioning instead of MERGE tables. The process I use involves using stored procedures to create and drop partitions. This article will go over the stored procedures I use; special thanks to Roland Bouman for taking a look and giving great feedback to optimize this process.

First, a simple table, not partitioned (yet):

use test;
DROP TABLE IF EXISTS my_part;
CREATE TABLE IF NOT EXISTS my_part (
  id int NOT NULL,
  creationDate datetime NOT NULL,
  PRIMARY KEY (id,creationDate)
) ENGINE=InnoDB;

In real, life there is more to the table than just id and creationDate. The most important part is that the partitioned field(s) need to be part of the primary key.

Now, add the partition definition. This can be done in the CREATE statement, but I have found that it is easier for me to think …

I’ve been wanting to write a backup script for a while now that does the following: reads the partition information for the directory that you are backing up into and computes the used/available/percentage-available space. Then it reads the total data size from the MySQL tables and ensures that you have enough space on disk (for [...]