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MySQL Replication – Multi-Threaded Slaves (Parallel Event Execution)

If you aren’t familiar with MySQL replication, “Replication enables data from one MySQL database server (the master) to be replicated to one or more MySQL database servers (the slaves). Replication is asynchronous by default – slaves need not to connected permanently to receive updates from the master. This means that updates can occur over long-distance connections and even over temporary or intermittent connections such as a dial-up service. Depending on the configuration, you can replicate all databases, selected databases, or even selected tables within a database.” (From: http://dev.mysql.com/doc/refman/5.5/en/replication.html).

I use MySQL replication on my home office server. I don’t really have much data to store, but it is nice to have several replicated slaves for backup purposes and also for testing new replication features of MySQL. I …

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2012 in review

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog. Here’s an excerpt: 4,329 films were submitted to the 2012 Cannes Film Festival. This blog had 21,000 views in 2012. If each view were a film, this blog would power 5 Film Festivals Click here to see the complete report.

MySQL@FOSDEM 2013: Call for papers closes in a few days!

This is just a reminder: Call for papers for MySQL & Friends devroom at FOSDEM 2013 is open until December 21st, which is this Friday. Please hurry up and submit your proposal. Possible topics include everything related to MySQL.

New optimization in MariaDB 10.0: EXISTS-to-IN subquery rewrite

MariaDB 10.0 has got another new feature: Sanja Byelkin has pushed EXISTS-to-IN rewrite feature. It is an optimization targeted at EXISTS subqueries. The idea behind it is simple. EXISTS subqueries often have form:

EXISTS (SELECT …  FROM … WHERE outer_col=inner_col AND inner_where)

where outer_col=inner_col is the only place where the subquery has references to outside. In this case, the subquery can be converted into an uncorrelated IN:

outer_col IN (SELECT inner_col FROM … WHERE inner_where)

The conversion opens new opportunities for the optimizer. Correlated EXISTS subquery has only one execution strategy. Uncorrelated IN subquery has two:

  1. re-run the subquery every time the subquery is evaluated (the same as in EXISTS)
  2. Materialize the subquery output …
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16 Table Join Benchmark Results Published

16 Table Join Benchmarks were ran at Amazon Web Services.

Results available at www.paralleluniverse-inc.com/benchmarks.shtml .

Using the MySQL Script mysqlfailover for Automatic Failover with MySQL 5.6 GTID Replication

This post is the second in a series that I will be doing on MySQL Workbench Utilities – Administer MySQL with Python Scripts. You may want to read the first half of this post to understand how MySQL Workbench Utilities work and how you access the scripts. These scripts were written by Chuck Bell (a MySQL employee) and are available as stand-alone scripts (see Chuck’s …

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On Big Data, Analytics and Hadoop. Interview with Daniel Abadi.

“Some people even think that “Hadoop” and “Big Data” are synonymous (though this is an over-characterization). Unfortunately, Hadoop was designed based on a paper by Google in 2004 which was focused on use cases involving unstructured data (e.g. extracting words and phrases from Webpages in order to create Google’s Web index). Since it was not [...]

MariaDB Foundation

You may have already seen the announcement MariaDB Foundation to Safeguard Leading Open Source Database. We at Open Query wholeheartedly support this (r)evolution of the MySQL ecosystem, which appears to be increasingly necessary as Oracle Corp is seriously dropping the ball with security updates and actually just general development and innovation. Oracle has actually done some very good work, I happily acknowledge that – but security issues are critical, having crashing bugs and incorrect query results in a .28 of a GA release is uncool, and not incorporating awesome development efforts by the community is just astonishing.

MariaDB is where the Sphinx fulltext …

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MariaDB security updates

Important Security Fix for a Buffer Overflow Bug: MariaDB 5.5.28a, 5.3.11, 5.2.13 and 5.1.66 include a fix for CVE-2012-5579, a vulnerability that allowed an authenticated user to crash MariaDB server or to execute arbitrary code with the privileges of the mysqld process. This is a serious security issue. We recommend upgrading from older versions as soon as possible.

MariaDB 5.5.28a, 5.3.11, 5.2.13 and 5.1.66 (GA) binaries, packages, and source tarballs are now available for download from http://downloads.mariadb.org. So you can upgrade within your own major series.

Note that while this fix has just been published, some other vulnerabilities have been noted over the weekend also. Below a summary of these other CVEs as documented by Red Hat Security Response Team, with annotations by Sergei Gulubchik who is the Security Coordinator for MariaDB.

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MariaDB C client libraries and the end of dual-licensing

Finally there is an LGPL C client library for MariaDB, and thus also for MySQL. Monty Program and SkySQL have been working on this for some time. Admittedly there was already the BSD licensed Drizzle client library which was also able to talk to a MySQL/MariaDB server, however its API is different. The C client library for MariaDB has exactly the same API existing applications are used to, so you can just re-link and keep going! There is also a new LGPL Java client library for MariaDB.

In case you don’t quite realise: this is actually a major thing.

At MySQL AB, the client library was made GPL and this flowed through to Sun Microsystems and then Oracle Corp. This licensing choice for the client library was the basis of the …

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