MySQL table alterations can interrupt production traffic causing bad customer experience or in worst cases, loss of revenue. Not all DBAs, developers, syadmins know MySQL well enough to avoid this pitfall. DBAs usually encounter these kinds of production interruptions when working with upgrade scripts that touch both application and database or if an inexperienced admin/dev engineer perform the schema change without knowing how MySQL operates internally.

Truths
* Direct MySQL ALTER table locks for duration of change (pre-5.6)
* Online DDL in MySQL 5.6 is not always online and may incurr locks
* Even with Percona Toolkit‘s pt-online-schema-change there are several workloads that can experience blocking

Here on the Percona MySQL …

Recently I had a need to determine the session value of a MySQL plugin variable in a core file.  Here I use the word plugin variable to refer to MySQL system variables provided by plugins.  While this is not a very difficult task, it is not as straight forward as printing a global variable. It took some time to figure out the layout of the plugin variables and get the needed information. This short article is to share this gdb tip with other interested MySQL developers and support engineers.

In this article, let us inspect the session value of the plugin variable innodb_strict_mode, which is of type boolean. Quite obviously, this plugin variable is provided by InnoDB storage engine.

The Quick Answer

…

It was very fun for me to read last week the announces about RDS Aurora - specially the parts related to its performance gain over MySQL: Aurora is claimed to show x5 times better performance than MySQL! However, without publishing any details about ;-) -- and the only details I was able to find until now and group together are the following:

• Aurora is a proprietary closed source database engine, "compatible" with MySQL (so, not an improved MySQL fork, as many expected..)
• Sysbench workloads were used to evaluate Aurora performance

• the only currently published Sysbench results are the following:

  • 500K SELECT/sec
  • 100K UPDATE/sec
…

Test Kitchen together with Vagrant is a wonderful way to test out your infrastructure deployment and orchestration code. It makes test-driven development especially easy by allowing you to test locally using virtual machines. However, those of you who do a lot of testing with Test Kitchen and Vagrant would know that waiting for tests to complete can be painfully long. This is especially true when with every test run the same packages have to be downloaded over and over again. Or when Vagrant decides to update the Virtual Box Guest Addition plugin every time you run your test suites.

Christine Draper has an excellent …

In the spirit of Movember, the database bloggers are also chipping in with their fair share of contribution, not only with a mo but also with the blog posts. This Log Buffer Edition encompasses that all.

Oracle:

Will the REAL Snap Clone functionality please stand up?

Oracle Linux images for Docker released.

In-depth look into Oracle API Catalog (OAC) 12c.

Patch Set Update: Hyperion Strategic Finance 11.1.2.3.504.

Rollback to …

Global Transaction ID (GTID) is one of the major features that were introduced in MySQL 5.6 which provides a lot of benefits (I have talked about the GTID concept, implementation and possible troubleshooting at Percona Live London 2014, you can download the slides from our presentations repository or from my session at Percona Live.
On the other hand, there are some important things you should consider before deploying GTID in production, I'm going to list them here in this blog post.

Table of Content

• …

This blog post was inspired by my visit at the annual Zabbix Conference in Riga, Latvia this year, where I gave a couple of talks on MySQL and beyond.

It was a two day single-track event with some 200 participants, a number of interesting talks on Zabbix (and related technologies) and really well-organized evening activities. I was amazed how well organized the event was and hope to be invited to speak there next year as well.   (Just in case you’re not sure what Zabbix is, it is an enterprise-class open source distributed monitoring solution for networks and applications)

I must secretly confess, it was also the first conference …

PROVSERVICE table on VMS ANYPROV has a column which is auto increment

+---------------------+--------------+------+-----+---------------------+----------------+

| Field               | Type         | Null | Key | Default             | Extra          |

+---------------------+--------------+------+-----+---------------------+----------------+

| PROVSERVICEID       | int(11)      | NO   | PRI | NULL                | auto_increment |

Development were getting an error suggesting an issue with the auto increment column

…

SINGLE USER:

To see which grants a user has do

show grants for sdas;

+-----------------------------------------------------------------------------------------------------+

| Grants for sdas@%                                                                                   |

+-----------------------------------------------------------------------------------------------------+

| GRANT USAGE ON *.* TO 'sdas'@'%' IDENTIFIED BY PASSWORD …

While playing with MySQL 5.7.5 on POWER8, I came across a rather interesting bug (74775 – and this is not the only one… I think I have a decent amount of auditing and patching to do now) which made me want to write a bit on memory barriers and the volatile keyword.

Memory barriers are hard.

Like, super hard. It’s the kind of thing that makes you curse hardware designers, probably because they’re not magically solving all your problems for you. Basically, as you get more CPU cores and each of them have caches, it gets more expensive to keep everything in sync. It’s quite obvious that with *ahem* an eventually consistent model, you could save a bunch of time and effort at the expense of shifting some complexity into software.

Those in the MySQL world should recognize this – we’ve been dealing with asynchronous replication for well over a decade …