Download Slides The second MySQL tutorial session at Oracle Open World was “MySQL Group Replication in a Nutshell” by MySQL Community Manager Frederic Descamps. This is succinctly described as: “Multi-master update anywhere replication for MySQL with built-in conflict detection and resolution, automatic distributed recovery, and group membership.

Percona announces the new release of Percona XtraDB Cluster 5.6.32-25.17 on October 4, 2016. Binaries are available from the downloads area or our software repositories.

Percona XtraDB Cluster 5.6.32-25.17 is now the current release, based on the following:

• Percona Server 5.6.32-78.1
• Galera Replication library 3.17
• Codership wsrep API version 25

Bugs Fixed:

• Fixed DONOR …

This blog post will discuss how to use the MySQL super_read_only system variable.

It is well known that replica servers in a master/slave configuration, to avoid breaking replication due to duplicate keys, missing rows or other similar issues, should not receive write queries. It’s a good practice to set

read_only=1

 on slave servers to prevent any (accidental) writes. Servers acting as replicas will NOT be in read-only mode automatically by default.

Sadly, 

read_only

 has an historical issue: users with the SUPER privilege can override the setting and could still run DML queries. Since Percona Server 5.6.21 and MySQL 5.7.8, however, you can use the

super_read_only

 feature to extend the

read_only

Optimiser is the brain of the RDBMS. Optimiser decides the right access method , algorithms , join order and right index to be used for better execution of the query. This blog is made to shed some lights on Cost based optimiser in MySQL 5.7. The cost or statistics are stored in the data dictionary .

What is cost-based optimization ?

• The cost model is based on estimates of cost various operations occur during query execution.

• The optimizer has a set of default “cost constants” it will make decision on execution plans.

• In MySQL 5.7, the optimizer has addition a database of cost estimates to use during the execution plan.

• These cost estimates are stored in server_cost & engine_cost tables in MySQL schema. For more details Cost Model

MySQL …

You must have heard about the CVE-2016-6662, the recent zero-day exploit exposed in most of MySQL and its variants. The vulnerability flaw can be exploited by a remote attacker to inject malicious settings into your my.cnf,. you can read about the details here.

At the moment, all supported MySQL vendors by ClusterControl (Oracle, Codership, Percona, MariaDB) have been patched with a bug fix and released in their respective package repository:

With Oracle Open World behind us, we are now getting ready for the next big event, i.e. the European edition of PerconaLive. I am going to be a presenter three times:

• MySQL operations in Docker is a three-hour tutorial, and it will be an expansion of the talk by the same title presented at OOW. Attendees who want to play along can do it, by coming prepared with Docker 1.11 or later and the following images already pulled (images with [+] are mandatory, while [-] are optional):

  …

The freshly released MySQL 8.0 includes a data dictionary, which makes MySQL much more reliable. Thanks to this features, we don't have any '.frm' files, and querying the information_schema is 30x to 100x faster than previous versions.

One drawback of the implementation is that the data dictionary tables are hidden by design.

While the reason is fully understandable (they don't want to commit on an interface that may change in the future) many curious users are disappointed, because openness is the basis of good understanding and feedback.

The problem to access the dictionary tables can be split in three parts:

• Finding the list of tables; …

BakaSQL: a bit of history When I joined this new company I was already aware there was a lot of work to do. There was no DBA Team to speak of; any MySQL related task was handled by the sysadmins, and the company was growing as fast as you can imagine, with 15-20 new employees arriving each month, most of them in the IT department. For sure, there was much fun ahead.

During my first week in the new job  I immediately felt that something was not right. I was receiving too much DMLs to execute each day, spanning a wide set of servers, schemas an tables. This is not something I had seen before, so I started asking around what the reason behind it was.  It turned out that there were multiple reasons behind it:

• there were known bugs in the applications that were never fixed
• application configuration items were stored in MySQL, but there was no admin panel to modify them
…

A customer showed that a particular client reported a less-than-helpful error message when it tried to display some meta-data about a table.

I couldn’t repeat the behavior with just a copy of the schema, so I suspected it was because of the size of data in the customer’s server – somebody had used an int where they needed a long.

The customer’s data was quite large – many hundreds of GB – more than I could easily whip up on my laptop to test. But, I didn’t really need all that data, or even any data at all; I just needed MySQL to pretend it had all that data. Specifically, I needed information_schema to report a large data_length.

Enter Rewriter, the query rewrite plugin that ships …

It is a common auditing requirement to log user connection events, including whether or not authentication was successful.
There are a number of alternatives available for MySQL, but unfortunately there is no built-in functionality at the time of this writing. In this post we will discuss auditing MySQL users with McAfee plugin, which is available under GPL Version 2 license.

Installation instructions

These apply to debian-based hosts, but instructions for red hat are similar.

1. Download latest plugin release from github.

At the time of this post for MySQL 5.5 you can get:

wget https://bintray.com/mcafee/mysql-audit-plugin/download_file?file_path=1.0.9-release%2Faudit-plugin-mysql-5.5-1.0.9-585-linux-x86_64.zip

2. Decompress …