Pythian Group

At Kscope this year, I attended a half day in-depth session entitled Data Warehousing Performance Best Practices, given by Maria Colgan of Oracle. In that session, there was a section on how to determine I/O throughput for a system, because in data warehousing I/O per second (iops) is less important than I/O throughput (how much actual data goes through, not just how many reads/writes).

The section contained an Oracle-specific in-database tool, and a standalone tool that can be used on many operating systems, regardless of whether or not a database exists:
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In October 2008, Baron posted How to Check MySQL Replication Integrity Continually. Here at Pythian we have developed a method based on that post, and added “verifying that masters and slaves are in sync” to our standard battery of tests.

We call it “Continual replication sync checking”. This article will explain how it works, how to test and make the procedure non-blocking, benchmarks from the real world, issues we encountered along the way, and finally Pythian’s procedure of setting up continual replication sync in a new environment.

At the 2010 MySQL User Conference & Expo, my co-worker Danil Zburivsky did a presentation about this, and you can get the slides in ODP (Open Office) format or watch the 46-minute video on YouTube.

How it works

On the master, mk-table-checksum is run. In order to make the checksum operation online, we use the modulo and offset features of mk-table-checksum to checksum only part of the data at a time. The checksum is run (from cron) on the master and replicates to the slave. The results are captured in a result table, and a separate process checks the result table and notifies us of any discrepancies.
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IOUG has a free series of three webinars on upgrading MySQL. Each webinar is an hour long, and it starts with a webinar by me tomorrow at 12 noon Central time (GMT-5) on “Why and How to Upgrade to MySQL 5.1″. The webinar assumes you are upgrading from MySQL 5.0 to MySQL 5.1, and talks a little bit about the new features, server variables, and what you need to know when upgrading to MySQL 5.1.

The software used is GoToWebinar (formerly GoToMeeting), so you will need to install that software. To register, use the links on the IOUG MySQL Upgrade Webinar Series page.

The complete list of webinars in the MySQL Upgrade Series is:
* MySQL 5.1: Why and How to Upgrade
Sheeri Cabral, The Pythian Group
Tuesday, July 27, 12:00 p.m. – 1:00 p.m. CT (GMT-5)

* MySQL Upgrades With No Downtime
Sean Hull, Heavyweight Internet Group
Wednesday, July 28, 12:00 p.m. – 1:00 p.m. CT (GMT-5)

* MySQL Upgrade Best Practices
Matt Yonkovit, Percona
Thursday, July 29, 12:00 p.m. – 1:00 p.m. CT (GMT-5)

(note, I am not sure if it is free for everyone or just free for IOUG members; my apologies if it is the latter)

One common question I get is how to use partitioning instead of MERGE tables. The process I use involves using stored procedures to create and drop partitions. This article will go over the stored procedures I use; special thanks to Roland Bouman for taking a look and giving great feedback to optimize this process.

First, a simple table, not partitioned (yet):

use test;
DROP TABLE IF EXISTS my_part;
CREATE TABLE IF NOT EXISTS my_part (
  id int NOT NULL,
  creationDate datetime NOT NULL,
  PRIMARY KEY (id,creationDate)
) ENGINE=InnoDB;

In real, life there is more to the table than just id and creationDate. The most important part is that the partitioned field(s) need to be part of the primary key.
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Yes, you read the title correctly — there are three editions of MySQL available, according to http://www.mysql.com/products/enterprise/server.html. Well, that page names two, and then of course there is the community edition….

From the manual page:

MySQL Enterprise Server is available in the following editions:

* MySQL Enterprise Server – Pro is the world’s most popular open source database that enables you to rapidly deliver high performance and scalable Online Transaction Processing (OLTP) applications.
* MySQL Enterprise Server – Advanced is the most comprehensive edition of MySQL. It provides all the benefits of MySQL Enterprise Server Pro and adds horizontal table and index partitioning for improving the performance and management of VLDBs (Very Large Databases).

How is “horizontal table and index partitioning” different from the regular partitioning available in MySQL 5.1?
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I wanted to get examples of some of the extra information that the Percona server has in its INFORMATION_SCHEMA metadata, and in doing so, I stumbled across an interesting MySQL bug/feature/point — INFORMATION_SCHEMA tables (which are actually system views) are case sensitive when used in comparisons:
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Ronald saved me a post by giving his feedback on a few Oracle conferences that now have MySQL content.

My opinion is pretty much a summary of Ronald’s post, so I won’t repeat it here. Instead, I’ll post about a conference he did not, the 4th Extremely Large Databases Conference. I am particularly interested in any MySQL folks planning to attend (I would expect Tokutek to be represented, and maybe even the Calpont folks).

Most of this is directly from an e-mail I received from Jacek Becla, who had a keynote at the 2008 MySQL User Conference and Expo. If you also received this e-mail, please feel free to skip ahead to my viewpoints on the various Oracle conferences (or just skip altogether).
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Ronald Bradford and I produced a successful MySQL track at Kaleidoscope (hereinafter referred to as Kscope). With a speaker list of Philip Antoniades, Josh Sled and Craig Sylvester of Oracle, Laine Campbell of PalominoDB, Patrick Galbraith of Northscale, Sarah Novotny of Blue Gecko, Padrig O’Sullivan of Akiba, Dossy Shiobara of Panoptic.com and Matt Yonkovic of Percona, we knew the technical content was going to be great.

As someone who’s helped organize all the OpenSQLCamps, a few MySQL Camps, and the Boston MySQL User Group, I know that participation at an event such as this can be small. Despite planning the MySQL track at the last minute, we had top-notch speakers with appropriate content for the audience, which was mostly Oracle crossovers. We had several registrants who came solely for the MySQL content, with all but 2 of the 27 sessions having 10-25 audience members. According to a few different folks, this is the same amount as the SOA and BPM track receives, and that track was not planned at the last minute. The ODTUG conference committee and board were happy with the turnout as well. I can’t wait to see the results of the evaluations!

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Today at Kaleidoscope I will be doing a 90-minute session comparing MySQL’s SQL syntax to the ANSI/ISO SQL:2003 standard, entitled What Do You Mean, “SQL Syntax Error”?

You can download the PDF slides now.
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MySQL does not follow the ANSI SQL standard for quoting. MySQL’s default quoting behavior is that either single or double quotes can be used to quote a string (this gets me into trouble when I work with Oracle databases, as double quotes do not indicate a string!).

mysql> SELECT 'alive';
+-------+
| alive |
+-------+
| alive |
+-------+
1 row in set (0.00 sec)

mysql> SELECT "alive";
+-------+
| alive |
+-------+
| alive |
+-------+
1 row in set (0.00 sec)

Bare words are dealt with in context; in this case, a bare word would be parsed as a column name:

mysql> SELECT alive;
ERROR 1054 (42S22): Unknown column 'alive' in 'field list'

Backquotes are the way MySQL escapes table names. So, if you want a reserved word, number or operator to be the name of an object (ie, a table named “1″ or a column named “date”) you need to use backquotes to avoid a syntax error….for example:
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