Part of my job at Percona is to perform customer audits.  I’ve had fun the last week getting up to speed on some of the great tools in the Percona Toolkit.  I’m sure people have talked about these before, but to be honest, I always found it hard to take the time to learn new tools, and at my previous job there were often a lot of tools in-house that made it easier to avoid learning something new.  The great thing about the Percona tools is that they aren’t environment dependent (as much as is possible), they typically only require Perl to run.

So, with that being said, I wanted to just go through a few of the tools I learned about this last week that I found useful.

pt-collect:

The collect script collects information.  A lot of information.  I ran it for 10 minutes on a customer’s server and …

Elastic, fantastic: click here to add a MySQL replication database cluster to your cloud configuration. Click - yes, we can! Just one little thing, you need to update your application: consistency model changed. Plan for it. Some thoughts for PECL/mysqlnd_ms 1.x, the PHP mysqlnd replication plugin.

Problem: C as in ACID is no more

A MySQL replication cluster is eventual consistent. All writes are to be send to the master. A write request is considered successful once the master has performed it.

If you’re in Nuremberg Germany next week (November 15-17th) and have anything to do with Oracle or their products, then the DOAG (German Oracle User Group) conference is the place to be. I will be representing SkySQL Ab at the conference, giving a talk about the internal architecture of MySQL Cluster. The talk will look at the internals of MySQL Cluster and at the different processes that ensure the High Availability of MySQL Cluster. Beyond that, the talk will also look at how the data is stored on the data nodes, how different types of queries are resolved in the cluster, and how a primary key lookup is executed differs significantly from a tree index search. The talk will also look at the resources involved in resolving the queries.
So if any of the above sounds interesting come and listen to my talk in room Singapur at 13:00 on Tuesday!

We are proud to share that OSSCube has now entered into a partnership with Cloudera, as the official training partner for Cloudera Developer Training for Apache Hadoop. The pride is, essentially, in the fact that we are the World’s First Cloudera / Hadoop Training Partner.

Cloudera provides enterprises a powerful new data platform built on the popular Apache Hadoop open source software package.  Hadoop is a powerful data management platform for consolidating your data, storing your information inexpensively and reliably and understanding large, heterogeneous data sets in order to better comprehend the data deluge.

OSSCube believes this partnership will deliver first-class Cloudera / Hadoop training to developers and IT professionals to help establish them as a trusted and valuable resource looking to work with Apache Hadoop, along with developing their professional skills.

Immediately after the …

We are proud to share that OSSCube has now entered into a partnership with Cloudera, as the official training partner for Cloudera Developer Training for Apache Hadoop. The pride is, essentially, in the fact that we are the World’s First Cloudera / Hadoop Training Partner.

Cloudera provides enterprises a powerful new data platform built on the popular Apache Hadoop open source software package.  Hadoop is a powerful data management platform for consolidating your data, storing your information inexpensively and reliably and understanding large, heterogeneous data sets in order to better comprehend the data deluge.

OSSCube believes this partnership will deliver first-class Cloudera / Hadoop training to developers and IT professionals to help establish them as a trusted and valuable resource looking to work with Apache Hadoop, along with developing their professional skills.

Immediately after the …

I have been following Virident for a long time (e.g. http://www.mysqlperformanceblog.com/2010/06/15/virident-tachion-new-player-on-flash-pci-e-cards-market/). They have great PCIe Flash cards based on SLC NAND.
I always thought that Virident needed to come up with an MLC card, and I am happy to see they have finally done so.

At Virident’s request, I performed an evaluation of their MLC card to assess how it handles MySQL workload. As I am very satisfied with the results, I wish to share my findings in this post.

But first, I wish to offer an overview of the card.

Virident FlashMax Cards are …

I ran into an issue installing the MySQLdb module.

>>> import MySQLdb
/Library/Python/2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.7-intel.egg/_mysql.py:3: UserWarning: Module _mysql was already imported from /Library/Python/2.7/site-packages/MySQL_python-1.2.3-py2.7-macosx-10.7-intel.egg/_mysql.pyc, but /Users/jhaddad/Downloads/MySQL-python-1.2.3 is being added to sys.path
Traceback (most recent call last):
File ““, line 1, in
File “MySQLdb/__init__.py”, line 19, in
import _mysql
File “build/bdist.macosx-10.7-intel/egg/_mysql.py”, line 7, in
File “build/bdist.macosx-10.7-intel/egg/_mysql.py”, line 6, in __bootstrap__
ImportError: dlopen(/var/root/.python-eggs/MySQL_python-1.2.3-py2.7-macosx-10.7-intel.egg-tmp/_mysql.so, 2): Library not loaded: …

Not a big deal, but I just added a “Table of Contents” page to my blog to make finding older articles much easier.

I noticed most of my posts are quite lengthy, and it can take a bit of searching/clicking to find an older entry. So unless you happen to recall the ‘month/year’ it was published, which I don’t even remember that, then hopefully this will help.

Really simple, and looks just like this:

• Microseconds and MariaDB
• Dealing with Assertion failure in log/log0recv.c – !page || (ibool)!!page_is_comp(page) == dict_table_is_comp(index->table)
• MySQL Windows Users – Use Grep to Search MySQL Source Code
• …

It's time for the next MariaDB developer meeting. This time it's in Athens from 11-November to 14'th of November.

The reason for choosing Athens was that the previous MariaDB developer meetings has been in places like Iceland, Spain and Portugal (all countries with some financial issues) and we thought it was no more than right to support Greece next.

As before, the meeting is open for everyone that wants to attend.

The agenda can be found here. This is also the place where all proposed and agreed to plans will be be posted.

We will try to keep the #maria IRC channel on Freenode up to date about what …

Today I saw a query like this:
SELECT d FROM t;

Performance was terrible. I ran out of patience after several minutes and killed the thread.

I changed the query to this:
(SELECT d FROM t) UNION ALL (SELECT NULL LIMIT 0);

It completed in under 3 seconds.

Can you explain how a no-op UNION so dramatically improved performance? (I couldn't have, without help from Jesper Krogh and James Day).

Hint #1 ▼

http://dev.mysql.com/doc/refman/5.5/en/cursor-restrictions.html

Hint #2 ▼

The field `d` is a varchar and is bigger than it needs to be.

Hint #3 ▼

http://dev.mysql.com/doc/refman/5.5/en/memory-storage-engine.html

Hint #4 ▼

http://dev.mysql.com/doc/refman/5.5/en/internal-temporary-tables.html

Answer ▼

The query is in a cursor. MySQL materializes …