Having big tables is one of the expected database problems, especially, for the fast growing database systems. In fact, big tables itself is not a problem but with big tables, the following problems are strongly expected:

1. Retrieving data from big tables is so slow.
2. It is a very hard job to maintain those tables like adding/removing an index, adding/dropping/modifying a column, … etc.
3. System resources, especially, the IO system might not be able to handle such huge traffic of writes and reads.
4. When it comes to the reporting queries, it might be a horrible nightmare!
5. Always cause disk space problem.

All the above problems will show up the need for scaling! So, let’s check out what are the possible solutions for that problem:

• MySQL Partitioning: Is a good solution but we will still face disk space and server resources problems. …

On a recent engagement I worked with a customer who makes extensive use of UUID() values for their Primary Key and stores it as char(36), and their row count on this example table has grown to over 1 billion rows.

The table is INSERT-only (no UPDATEs or DELETEs), and the bulk of their retrieval are PK lookups. Lookups by PK were performing acceptably, but they were concerned with the space usage by the table as we were approaching 1TB (running with innodb_file_per_table=1 and Percona Server 5.5).

This schema model presents an increasing burden for backups since they use Percona XtraBackup, and so the question was asked: does their choice of an effectively random Primary Key based on UUID() impact their on-disk storage, and to what extent? And as a neat trick I show towards the end of this post how you can calculate the …

The Ubuntu 12.04.3 LTS release only provides MySQL 5.1 and MySQL 5.5 using the default Ubuntu package manager.

Oracle (owners of the MySQL(tm)) now provide Debian/Ubuntu APT repositories for all GA and DMR versions of MySQL including supporting Ubuntu 12.04.

The following steps demonstrate upgrading from the Ubuntu 5.5 server package to the Oracle 5.6 server package.

Verify MySQL Packages

$ apt-cache search mysql-server
mysql-server - MySQL database server (metapackage depending on the latest version)
mysql-server-5.5 - MySQL database server binaries and system database setup
mysql-server-core-5.5 - MySQL database server binaries
auth2db - Powerful and eye-candy IDS logger, log viewer and alert generator
cacti - Frontend to rrdtool for monitoring systems and services
torrentflux - web based, feature-rich BitTorrent download manager

Verify …

As part of a MySQL 5.5 to MySQL 5.6 upgrade across several Ubuntu servers of varying distros an audit highlighted a trivial but interesting versioning identification error in Ubuntu’s packaging of MySQL.

Ubuntu 12.04 LTS

$ sudo dpkg -l | grep mysql-server-5.5
ii  mysql-server-5.5   5.5.41-0ubuntu0.12.04.1  ...

$ mysql -uroot -p -e "SELECT VERSION()"
+-------------------------+
| VERSION()               |
+-------------------------+
| 5.5.41-0ubuntu0.12.04.1 |
+-------------------------+

But when you look at the mysql --version it does NOT say 5.5.41.

$ mysql --version
mysql  Ver 14.14 Distrib 5.5.34, for debian-linux-gnu (x86_64) using readline 6.2

Ubuntu 14.04 LTS

On 14.04 I get expected results.

$ sudo dpkg -l | grep mysql-server-5.5
ii  mysql-server-5.5       5.5.41-0ubuntu0.14.04.1   ...

rbradfor@rubble:~$ mysql -uroot -p -e "SELECT VERSION()" …

MySQL 5.6 will now automatically recreate the InnoDB redo log files during a MySQL restart if the size (or number) of these logs changes, i.e. a change to innodb_log_file_size. See Changing the Number or Size of InnoDB Log Files which states “If InnoDB detects that the innodb_log_file_size differs from the redo log file size, it will write a log checkpoint, close and remove the old log files, create new log files at the requested size, and open the new log files.”

Before MySQL 5.6 it was necessary to stop MySQL and remove the InnoDB log files manually before restarting MySQL.

The error log shows:

tail -f /mysql/log/error.log
...
2015-03-28 21:51:25 3767 [Warning] InnoDB: Resizing redo log from 2*3072 to 2*65536 pages, LSN=1626017
2015-03-28 21:51:25 3767 [Warning] InnoDB: Starting to delete and …

Mermaids have the same probability of fixing your permission problems, but people continue believing in the FLUSH PRIVILEGES myth.I see suggesting the usage of FLUSH PRIVILEGES every time someone writes a tutorial or a solution to a problem regarding creating a new account or providing different privileges. For example, the top post on /r/mysql as of the writing of these lines, “MySQL:The user specified as a definer does not exist (error 1449)-Solutions” has multiple guilty cases of this (Update: the user has corrected those lines after I posted this article).

It is not my intention to bash that post, but I have seen …

Check Out Our Latest Technical Resources for MySQL, MariaDB, Postgres and MongoDB.

This blog is packed with all the latest resources and tools we’ve recently published! Please do check it out and let us know if you have any comments or feedback.

New Technical Live Webinar

• What: Deep-dive into How to Monitor Galera Cluster
• When: Tuesday April 21st
• Who: Krzysztof Książek, Senior Support Engineer, Severalnines
• Where: Register Here

Join our colleague Krzysztof Książek for a deep-dive session what to monitor in Galera Cluster for MySQL & MariaDB. Krzysztof is a MySQL DBA with experience managing complex database environments for companies like Zendesk, …

Can we output content of a mariaDB table into JSON using the CONNECT Storage Engine ? MariaDB and MySQL are not currently JSON friendly databases. The usage of JSON in MySQL is almost inexistent with the excetion of the explain JSON output and of MariaDB dynamic column dump. There also exist a few udf (in [...]

Years ago when I worked for the MySQL Support organization at the original MySQL AB, we spoke about MySQL Support as insurance and focused on a value proposition similar to that of car insurance. For your car to be fully covered, you must purchase car insurance before the incident happens – in fact most places around the world require automobile insurance. Similarly with many organizations, any production-use technology might be mandated to have its own insurance in the way of 24/7 support.

I think however this is a very one-sided view that does not capture the full value (and ROI) that a MySQL Support contract with Percona provides. Let’s look at the different dimensions of value it provides based on the different support cases we have received throughout the years.

Reduce and Prevent …

Thu, 2015-04-02 12:02jean-françoisgagné

(The previous post, Better Parallel Replication for MySQL, is Part 1 of the series.) Parallel replication is a much expected feature of MySQL. It is already available in MariaDB 10.0 and in MySQL 5.7. In this post, a very nice side effect of the MariaDB implementation is presented: Slave Group Commit.

(If you are not familiar with parallel replication and its implementation, read the previous post in this series to better understand this post.)

To allow better parallelization on slaves, MariaDB 10.0 and MySQL 5.7 have parameters that control the commit group sizes on the master. Those parameters are …