I recently worked on a customer case where at seemingly random times, inserts would fail with Innodb error 139. This is a rather simple problem, but due to it’s nature, it may only affect you after you already have a system running in production for a while.

Suppose you have the following table structure:

CREATE TABLE example (
id INT UNSIGNED NOT NULL AUTO_INCREMENT,
fname TEXT NOT NULL,
fcomment TEXT,
ftitle TEXT NOT NULL,
fsubtitle TEXT NOT NULL,
fcontent TEXT NOT NULL,
fheader TEXT,
ffooter TEXT,
fdisclaimer TEXT,
fcopyright TEXT,
fstylesheet TEXT,
fterms TEXT,
PRIMARY KEY (id)
) Engine=InnoDB;

Now you insert some test data into it:
mysql> INSERT INTO example
-> VALUES (
->   NULL,
->   'First example',
->   'First comment',
->   'First title',
->   'First subtitle',
->   'First …

With Paul McCullagh’s PBXT storage engine getting integrated into MariaDB 5.1, it’s never been easier to it out. So we have, on a slave off one of our own production systems which gets lots of inserts from our Zabbix monitoring system.

That’s possibly an ideal usage profile, since PBXT is a log based engine (simplistically stated, it indexes its transaction logs, rather than rewriting data from log into index and indexing that) so it should require less disk I/O than say InnoDB. And that means it should be particularly suited to for instance logging, which have lots of inserts on a sustained basis. Note that for short insert burst you may not see a difference with InnoDB because of caching, but sustain it and then you can notice.

Because PBXT has such different/distinct architecture there’s a lot of learning involved. Together …

I just spotted the youtube video of my OpenSQL Camp (Portland 2009) talk on An Open Storage Engine API. I talked about some of technical issues for implementing storage engines across many SQL front ends, not just MySQL.

You can find this talk and other mostly technical material at http://tokutek.com/technology/.

Here’s something that’s not really documented anywhere (unless you count ha_innodb.cc as a source of server documentation). You may have some idea about the MySQL/Drizzle row buffer format. This is passed around the storage engine interface: in for write_row and update_row and out for the various scan and index read methods.

If you want to see the docs for it that exist in the code, check out store_key_val_for_row in ha_innodb.cc.

However, there is another format that is passed to your engine (and that your engine is expected to understand) and for lack of a better name, I’m going to call it the key tuple format. The first place you’ll probably see this is when implementing the index_read function for a Cursor (or handler in MySQL speak).

You get two things: a pointer to the buffer and the length of the buffer. Since a key can be made up of multiple parts, some of which can be NULL and some of which can be of …

The NoSQL/relational database debate has been going on for quite some time. MariaDB, like MySQL is relational. And if you read these series of blog posts, you’ll realise that if you use MySQL correctly, you can achieve quite a lot.

1. It all starts with Kellan Elliott-McCrea with his introductory post on Using, Abusing and Scaling MySQL at Flickr. Follow the entire series.
2. He starts of the series with Ticket Servers: Distributed Unique Primary Keys on …

OpenSQLCamp was a huge success! I took videos of most of the sessions (we only had 3 video cameras, and 4 rooms, and 2 sessions were not recorded). Unfortunately, I was busy doing administrative stuff for opensqlcamp for the opening keynote and first 15 minutes of the session organizing, and when I got to the planning board, it was already full….so I was not able to give a session.

• 
  
• Comparing Non-Relational Databases: MongoDB, Tokyo Tyrant, CouchDB by Igal Koshevoy of Pragmaticraft

OpenSQLCamp was a huge success! Not many folks have blogged about what they learned there….if you missed it, all is not lost. We did take videos of most of the sessions (we only had 3 video cameras, and 4 rooms, and 2 sessions were not recorded).

All the videos have been processed, and I am working on uploading them to YouTube and filling in details for the video descriptions. Not all the videos are up right now….right now all the lightning talks are up.

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• All the lightning talks belowin one continuous video (just over 54 minutes total)
  
• The Graph Engine (Antony Curtis)
  
• …

Following on from our earlier announcement, Paul McCullagh has responded with the answers to your questions - as well as a few I gathered from other Percona folks, and attendees of OpenSQL Camp. Thank you Paul!

What’s the "ideal" use case for the PBXT engine, and how does it compare in performance?  When would I use PBXT instead of a storage engine like MyISAM, InnoDB or XtraDB?

Unfortunately it is not possible to point to a specific category of applications and say, "PBXT will be better here, so try it".  PBXT is a general purpose transactional storage engine, designed to perform well on a broad range of tasks, much like InnoDB.  However, PBXT's log-based architecture makes performance characteristics different to both MyISAM and InnoDB/XtraDB. Tests show that PBXT's performance is similar to InnoDB but, depending on your database designed and the application, it can be faster.

PBXT is a …

I forwarded on a list of questions about PBXT to Paul McCullagh today.  While Paul's busy answering them, I'd like to announce that Robert Dempsey (InfiniDB storage engine) and Bradley C. Kuszmaul (TokuDB storage engine) have also accepted an interview. If you have any questions about either storage engine, please post them here by Friday 20th November.

Entry posted by Morgan Tocker | No comment

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