The latest from the MySQL community

If you’re attending the conference, be sure to stay the extra day (this Friday) for the SkySQL and MariaDB Consulting Lounge and Solutions Day.

You can register for the Free Solutions Day here (just name, email, company, and country):

http://www.skysql.com/mysql-solutions-day

And if you’re around that day, there will be a SkySQL and MariaDB Consulting Lounge open all day long, so feel free to stop by and speak directly with the SkySQL and MariaDB Experts.

More about the Consulting Lounge can be found here too.

Just yesterday, I’m sure many saw Twitter opensourcing their MySQL implementation. It is based on MySQL 5.5 and the code is on Github.

For reference, the database team at Facebook has always been actively blogging, and keeping up their code available on Launchpad. Its worth noting that the implementation there is based on MySQL 5.0.84 and 5.1.

At Twitter, most of everything persistent is stored in MySQL – interest graphs, timelines, user data and those precious tweets themselves! At Facebook, its pretty similar – all user interactions like likes, shares, status updates, requests, etc. are all stored in MySQL ( …

We are pleased to announce the immediate availability of MariaDB 5.3.6. This stable (GA) release incorporates MySQL 5.1.62, some performance improvements, and several bug fixes.

Most importantly, MariaDB 5.3.6 includes a fix for a bug which, under certain rare circumstances, allowed a user to connect with an invalid password. This is a serious security issue. We recommend upgrading from older versions as soon as possible.

• MariaDB 5.3.6 Release Notes
• MariaDB 5.3.6 Changelog
• MariaDB 5.3.6 …

We are pleased to announce the immediate availability of MariaDB 5.1.62 and MariaDB 5.2.12. Both of these stable (GA) releases incorporate MySQL 5.1.62 and several bug fixes.

Most importantly, MariaDB 5.1.62 and 5.2.12 include a fix for a bug that under certain rare circumstances allowed a user to connect with an invalid password. This is a serious security issue. We recommend upgrading from older versions as soon as possible.

Please see the What is MariaDB 5.1 page for an overview of MariaDB 5.1, and the What is MariaDB …

This is the third blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is targeted at the join related optimizations introduced in the optimizer. These optimizations are available in both MySQL 5.6 and MariaDB 5.5, and MariaDB 5.5 has introduced some additional optimizations which we will also look at, in this post.

Now let me briefly explain these optimizations.

Batched Key Access

Traditionally, MySQL always uses Nested Loop Join to join two or more tables. What this means is that, select rows from first table participating in the joins are read, and then for each of these rows an index lookup is performed on the second table. This means many point queries, say for example if table1 yields 1000 …

Cloud databases have a memory problem.   Continuent has been doing a lot of Amazon deployments lately, and it is becoming apparent that memory utilization in those environments is more than just an inconvenience.  In this article I would like to discuss the memory problem that we see in customer implementations and some new features of Tungsten Enterprise that help alleviate it for MySQL.

The Cloud Memory Problem and Database Arrays

As I discussed in a recent article about prefetch, the amount of RAM allocated to the InnoDB buffer pool is one of the principle determinants of MySQL performance.  The speed difference between using a page in the buffer pool …

Update: MariaDB 5.1.62 and 5.2.12 have been released. They contain an important security fix.

We are pleased to announce the immediate availability of MariaDB 5.1.61 and MariaDB 5.2.11. Both of these stable (GA) releases incorporate MySQL 5.1.61 and several bug fixes.

Please see the What is MariaDB 5.1 page for an overview of MariaDB 5.1, and the What is MariaDB 5.2 page for an overview of MariaDB 5.2.

Sources, binaries, …

When I was at MySQL, I took for granted that pretty much every website I used had software at the back of it that was basically MySQL. It was a nice feeling. MariaDB is a lot younger, so when I was in Paris and had to make a payment for the taxi I was sitting in, I smiled a little when I saw that Paybox Services was processing my transaction. Some might recall that Paybox Services deployed MariaDB, since the 5.2 release. It was a wonderful feeling that somewhere in that transaction, MariaDB was behind it!

Paybox wanted some features inside of MySQL 5.5 and have been holding out for MariaDB 5.5. Its kind of nice to see that today, …

We are pleased to announce the immediate availability of MariaDB 5.5.22-rc. MariaDB 5.5.22 is the first release candidate (RC) release in the 5.5 series and follows the MariaDB 5.5.20-alpha and 5.5.21-beta releases. We hope to follow it up soon with a Stable (GA) 5.5 release.

MariaDB 5.5 is a merge of MariaDB 5.3 and MySQL 5.5 with some limited additional bug fixes. Please see the What is MariaDB 5.5 page for an overview of MariaDB 5.5.

The Release Notes page has some notes on the release. There is also a Changelog available for those who are interested.

…

MySQL version 4.1 was quite revolutionary. The main reason for that was support for sub-queries.1

However since then MySQL users were rather discouraged to use that functionality, basically due to the implementation’s poor performance  and forced to build complicated queries based on joins rather than on subqueries.

Of course you can do some effort to optimize your subquery with sometimes very good results2. Not always it’s easy or even possible if you can’t change the code though.

You’d say it’s not a problem for typical OLTP, web based traffic at all, just don’t use subqueries! That’s true, …