Everyone who works with MySQL (or MariaDB) query optimizer has to spend a lot of time looking at EXPLAIN outputs. You typically first look at the tabular form, because it is easier to read. You can immediately see what the join order is, what numbers of records will be read, etc:

MariaDB [dbt3sf1]> explain select * from customer, orders where c_custkey= o_custkey;
+------+-------------+----------+------+---------------+-------------+---------+----------------------------+--------+-------+
| id   | select_type | table    | type | possible_keys | key         | key_len | ref                        | rows   | Extra |
+------+-------------+----------+------+---------------+-------------+---------+----------------------------+--------+-------+
|    1 | SIMPLE      | customer | ALL  | PRIMARY       | NULL        | NULL    | NULL                       | 150303 |       |
|    1 | SIMPLE      | orders   | ref  | i_o_custkey   | i_o_custkey | 5       | …

Now that Percona XtraDB Cluster 5.6 is out in beta, I wanted to start a series talking about new features in Galera 3 and PXC 5.6.  On the surface, Galera 3 doesn’t reveal a lot of new features yet, but there has been a lot of refactoring of the system in preparation for great new features in the future.

Galera vs MySQL options

wsrep_provider_options is a semi-colon separated list of key => value configurations that set low-level Galera library configuration.  These tweak the actual cluster communication and replication in the group communication system.  By contrast, other PXC global variables (like ‘wsrep%’) are set like other mysqld options and generally have more to do with MySQL/Galera …

What do swaying palms, turquoise water, white sandy beaches and absolutely pristine fauna remind you of? Correct! It’s Log Buffer. This Log Buffer brings you beads of blog posts related to data dexterity crafted by leading bloggers across the planet.

Oracle:

When are Exadata’s storage indexes used?

Oracle 12c has increased the maximum length of character-based columns to 32K bytes.

Oracle has extended the maximum length of varchar2, nvarchar and raw columns to 32K, but this comes with some challenges when it comes to indexing such columns.

…

Last week, during Tomas' keynote at MySQL Percona Live Conference in London we announced as one of "previews" of the following MySQL 5.7 release(s) -- an over 1,000,000 Query/sec result obtained with InnoDB Memcached plugin on a Read-Only workload. This article here is just to confirm the announced results without going too much in details..

In fact we have no idea yet for today what are exactly the scalability and performance limits for this solution.. The huge gain in performance was possible here due initial overall speed-up made recently in MySQL 5.7 and letting us reach 500K …

The MariaDB project is pleased to announce the immediate availability of MariaDB 5.5.34. This is a Stable (GA) release. See the Release Notes and Changelog for detailed information on this release and the What is MariaDB 5.5? page in the MariaDB Knowledge Base for general information about the MariaDB 5.5 series.

Download MariaDB 5.5.34

Release Notes Changelog …

Recently, I helped a client that was having issues with deployments causing locking in their production databases.  At a high level, the two key components used in the environment were:

• Capistrano (scripted deployments) [website]
• Liquibase (database version control) [website]

At a high level, they currently used a CLI call to Liquibase as a sub-task within a larger deployment task.  The goal of this engagement was to modify that sub-task to run Liquibase in a non-blocking fashion as opposed to the default that just runs native ALTERS against the database.

As I wasn’t very familiar with Liquibase, I took this opportunity to learn more about it and it seems like a very valuable tool.  Essentially, it does the following:

• Adds two version control tables to …

Percona is glad to announce the first Beta release of Percona XtraDB Cluster 5.6 on November 21st, 2013. Binaries are available from downloads area or from our software repositories.

Based on Percona Server 5.6.14-62.0 including all the bug fixes in it, Galera Replicator 3.1 and on Codership wsrep API 5.6.14-25.1 is …

Next week the US celebrates Thanksgiving Day. For those that are American or live here, this is a significant event. Three different experiences recently have lead me to write this request for ALL MySQL community members to give thanks to those that have contributed to the MySQL ecosystem. I have made a commitment to myself, and I would like to challenge others to write one book review per week in December, that’s 4 book reviews to the MySQL books that I have on my bookshelf that have made an impact in some way. I ask others to give it a go too.

It only takes a few minutes to pen a comment on Amazon, or a publishers site, but to authors it means so much more. I can only speak for myself, but any comment; good, bad or ugly; helps to know you are out there and you took the time to acknowledge somebody’s work of art (in this case a publication).

I only have to look at my bookshelf and I find the following MySQL books (in …

It is a rather frequent problem to have to manage Virtual IP addresses (VIPs) with a Percona XtraDB Cluster (PXC) or with MySQL master HA (MHA). In order to help solving these problems, I wrote a Pacemaker agent, mysql_monitor that is a simplified version of the mysql_prm agent. The mysql_monitor agent only monitors MySQL and set attributes according to the state of MySQL, the read-only variable, the slave status and/or the output of the clustercheck script for PXC. The agent can operate in 3 modes or cluster types: replication (default), pxc and read-only.

The simplest mode is read-only, only the state of the read_only variable is looked at. If the node has the read_only variable set to OFF, then the writer is set to 1 and reader attributes is set to 1 while if the node has read_only set to ON, the writer attributes will …

The binary and source versions of MySQL Cluster 7.3.3 have now been made available at http://www.mysql.com/downloads/cluster/.

A description of all of the changes (fixes) that have gone into MySQL Cluster 7.3.3 (compared to 7.3.2) is available from the 7.3.3 Change log.