In the December episode of our “Meet The MySQL Experts” podcast, we chose to focus on MySQL Technical Support. Todd Farmer, Director of Oracle’s MySQL Global Support team, gives us insights into his organization, talking about who Oracle’s MySQL Support engineers are, how they help customers on a day-to-day basis, how they interact with the MySQL engineering and the bugs verification teams, and more…

Listen to the podcast to learn more about this team of MySQL Experts!

To better understand the value Oracle Premier Support for MySQL represents for your organization, get our white paper “Oracle Premier Support for MySQL: Rely on The …

I see a lot of people coming by #centos and similar channels asking for help when they’re experiencing a problem with their Linux system. It amazes me how many people describe their problem, and then say something along the lines of, “and I disabled SELinux...”. Most of the time SELinux has nothing to do with the problem, and if SELinux is the cause of the problem, why would you throw out the extra security by disabling it completely rather than configuring it to work with your application?

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Not everyone may know this, but there are precious few innodb crash recovery tests available.

Some folks have noticed this and asked for something to be done about it, but unfortunately, no tests have been created for the main MySQL branch.

The MySQL at Facebook branch has a number of tests that are quite interesting.  They basically create a master-slave pair, subject the master to a transactional load, crash the master, restart it, then ensure the master and slave are in sync (once the test load is stopped).

The team at Percona has been known to tinker with Innodb now and again, and were also very interested in having some tests to ensure …

Today is my final day working on MySQL. It has been an amazing 4.5 years, and I’ve loved working on the technical challenges involved in producing a piece of software which runs on so many different platforms, as well as working with so many talented individuals. I have learned a lot, which is just how I like it.

Times have changed since I first joined MySQL AB, of course. But despite going through two acquisitions, the day to day work hasn’t changed much at all. I still get to work from home, which is something I am passionate about and feel many companies are missing out on massively by still being stuck in an outdated 20th century mindset. Oracle have continued to invest in MySQL, providing additional headcount and extra hardware. And the vast majority of people I started working with back in 2007 are still with the company (don’t believe the FUD, folks) and working harder than ever.

I’m most proud of the work we have …

MySQL 5.6.4 milestone is here and I'd like to share some benchmark results I've obtained with it on dbSTRESS workload.

First of all, I was curious to observe a single user session performance (I did not look on it for a while, and there were several persons reporting we got a performance degradation in 5.6 comparing to 5.5 and 5.1).. - Seems it's very workload depending, because on dbSTRESS I've obtained the following:

Read-Only :

• 5.1 : 1800 TPS
• 5.5 : 1750 TPS (but sometimes jumps to 2700 TPS)
• 5.6.2: 2600 TPS
• 5.6.4: 2600 TPS

Read-Write :

• 5.1: 2700 TPS
• 5.5: 2600 TPS
• 5.6.2 : 3300 TPS
• 5.6.4: 3300-3600 TPS

The results as they are, I'm planning to profile them to analyze in depth (and periodic jumps to 2700 TPS on read-only in 5.5 are looking confusing). However, few …

Those variables are  easy to tune.

The evidence popup here between 128 and 256K for in memory workload.

My SQL SQL layer is optimistic and think that data will come from the storage engine at the speed of the memory bus , but in practice for IO bound workload and range scan in the table order it could not be the case , for MyISAM when reading from tables on disk, IOs are aligned on the read buffer so it may be of an intrest to increase it here.

In myisam.cc my_default_record_cache_size is set to  global_system_variables.read_buff_size;

To show IO size :
strace -p id_mysqld -e read -e write

If  monitoring smaller IO  request size from iostat  -xm, it may be that you are …

How to convert DBF to CSV files:

1) Install PERL, DBI, and DBD::XBase (comes as a package for many Linux distributions). 2) Use a script like this one:

#!/usr/bin/perl
use DBI;

my $dbh = DBI->connect("DBI:XBase:/directory/of/dbf/file") or die;
my $sth = $dbh->prepare("select * from YourDbfNameWithoutFileExtension") or die;
$sth->execute() or die $sth->errstr();

# adapt column names
print "Col1Name,Col2Name,Col3Name\n";

my @data;
while (my @data = $sth->fetchrow_array()) {
    print join(",",@data)."\n";
}

3) Call this script and redirect stdout to the CSV file.

Note: this article was originally published on http://blogs.innodb.com on Dec 20, 2011 by Vasil Dimov.

Last month we did a few improvements in InnoDB memory usage. We solved a challenging issue about how InnoDB uses memory in certain places of the code.

The symptom of the issue was that under a certain workloads the memory used by InnoDB kept growing infinitely, until OOM killer kicked in. It looked like a memory leak, but Valgrind wasn’t reporting any leaks and the issue was not reproducible on FreeBSD – it only happened on Linux (see Bug#57480). Especially the latest fact lead us to think that there is something in the InnoDB memory usage pattern that reveals a …

One of the best things that can happen to a piece of software is for people to actually use it.

I’ve been fortunate enough to have received feedback on the tool from several members of both the Percona and Drizzle teams.  The most common and strongly emphasized comments were in regards to what a terrible, terrible name dbqp really is in terms of saying, seeing, and typing it ; )

As that isn’t something that can be disputed (it’s really annoying to use in conversations *and* to type several dozen times a day), the project has been renamed to kewpie.  For those that follow such things, I did present on …

Note: this article was originally published on http://blogs.innodb.com on Dec 20, 2011 by Sunny Bains.

The problem and its cause

There have been several complaints over the years about InnoDB’s inability to scale beyond 256 connections. One of the main issues behind this scalability bottleneck was the read view creation that is required for MVCC (Multi Version Concurrency Control) to work. When the user starts a transaction this is what InnoDB does under the hood:

• Create or reuse a transaction instance – usually it is reused, the transactions are reused from a pool (trx_sys_t::mysql_trx_list).
• Initialize the transaction start time and assign a rollback segment
• Append the transaction to an active  transaction list ordered on trx_t::id in descending order

The …