Wordpress is a very popular Content Management System, usually built on top of a MySQL Database. Recently I attended a local Wordpress user group an that started me wondering what the database tables look like. So I installed a new Wordpress installation on a Ubuntu test box running MySQL 5.6.2.

Wordpress creates eleven tables: wp-commentmeta, wp_comments, wp_links, wp_options, wp_postmeta, wp_posts, wp_term_relationships, wp_term_taxonomy, wp_terms, wp_usermeta, and wp_users.

MySQL Workbench generated an EER Model you can see nearby. The first thing that caught me eye was the use of unsigned BIGINTs in every table as keys. Usually you want to use the smallest data type you can for keys. The smaller the key, usually the fast the system …

I’m sure most of you have seen the following error, and in many cases it’s quite easy to diagnose, as the error message is clear:

111111 11:11:11 [ERROR] MySQL is trying to open a table handle but the .ibd file for
table test/t does not exist.
Have you deleted the .ibd file from the database directory under
the MySQL datadir, or have you used DISCARD TABLESPACE?
See http://dev.mysql.com/doc/refman/5.1/en/innodb-troubleshooting.html
how you can resolve the problem.

From the client side, you may see something like:

ERROR 1146 (42S02): Table 'test.t' doesn't exist

However, if you know you (or some backup/archive script) did not delete the file, nor did you run ALTER TABLE table DISCARD TABLESPACE, then what else could cause this?

Well, I recently found a case where it could occur when a truncate table (on an InnoDB table using the plugin with no foreign keys – so fast truncate method is used, and …

Wine users reported this a couple of times in HeidiSQL's bug tracker, and also on WineHQ there were several reports for the same thing found: black color on icon areas which should be transparent. Cosmetic though quite annoying for a GUI which provides important buttons on a main toolbar. Wine 1.3.33 says this is fixed now, as stated on WineHQ.

At the le MUG some questions raised on TokuDB, i hope this post will answer more in deph details

InnoDB like any other general purpose RDBMS can be really bad for online back-office with big tables, despite following some usual practice and OLTP normalize schema.

• Having indexes in memory
  
• Touching a minimum set of rows for secondary index scan
  
• Scanning some range in primary key order      
  

This happen frequently when

• The working dataset is growing 2 to 100 times the size of the hardware memory
  
• Joining big tables jumping from secondary indexes to clustered table
  
• Increase concurrency on a big tables with range scan starting from a random point in the PRIMARY KEY   
  

It can be …

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Today we will get MySQL Cluster running on a single node.

A few years ago I created as presentation on running MySQL Cluster 5.1 on a laptop using Virtualbox that has proven to be the most popular download from NorthTexasMySQL.org with over nine hundred downloads.  Now MySQL 7.2 is in development milestone release and I find that I have some catching up to do.

Those of you with access to the Carrier Grade Edition (CGE) of Cluster, check out MySQL Cluster Manager 1.1 and Andrew Morgan’s  blog.  You can set up a cluster with minimal editing of configuration files or perform online software upgrades.

But MySQL Cluster 7.2 from Labs.MySQL.com is not CGE.  I started reading other …

I ask Sheeri of the OurSQL podcast to publish her list of MySQL websites and podcasts she follows. I thought it was only fair I do the same.  If you don’t watch these all the time your missing out. I read most of these every week.

If I missed one please leave a comment.

Planet MySQL – http://planet.mysql.com/  - This is the big community list of MySQL info.  Not all my list is found here.
OurMySQL - http://www.oursqlcast.com/ – This a THE podcast for MySQL.  New shows each week.
Sergey Petrunia’s blog – http://s.petrunia.net/blog/
clever elephant – http://blog.cleverelephant.ca/
…

In this podcast we talk about how to keep up with the MySQL ecosystem, and introduce a new segment. We invite you to let us know how you keep up, too. And we've updated our theme song!

News
The Meet the MySQL Experts podcast is now on iTunes. So now you can subscribe to the feedburner feed or to the iTunes feed.

Call for papers for Percona Live: MySQL Conference & Expo 2012 is open until Monday, December 5th. The MySQL Conference & Expo is Tuesday April 10 - Thursday, April 12, 2012 in Santa Clara, CA. To submit a paper, first register as a speaker at http://www.percona.com/live/mysql-conference-2012/user/register and then go to My …

We’re told that foreign key constraints are the best way to enforce logical referential integrity (RI) in SQL, preventing rows from becoming orphaned.  But then we learn that the enforcement of foreign keys incurs a significant performance overhead.1,2

MySQL allows us to set FOREIGN_KEY_CHECKS=0 to disable enforcement of RI when the overhead is too high.  But if you later restore enforcement, MySQL does not immediately scan all your data to verify that you haven’t broken any references while the enforcement was disabled.  That’s undoubtedly …

Rapid7 secures new funding. Microsoft drops Dryad. And more.

# Rapid7 secured $50m in series C funding.

# Microsoft confirmed that it is ditching its Dryad project in favour of Apache Hadoop.

# Arun Murthy provided more details of Apache Hadop 0.23.

# The Google Plugin for Eclipse and GWT Designer projects are now fully open source.

# openSUSE released version 12.1.