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IUS MySQL – how to enable the Archive storage engine

IUS is a great way of getting more recent versions of PHP and MySQL onto a Red Hat Enterprise Linux (RHEL) or Centos server than are normally available – without the trouble of having to compile them yourself.

Here is how to add the Archive storage engine to IUS MySql. This applies to MySQL 5.1.41 but will probably be the same for subsequent versions.

  1. Install the Archive storage engine as a plugin:
    yum install mysql51-plugins-archive*
  2. Tell MySQL to include the plugin via a client program:
    INSTALL PLUGIN ARCHIVE SONAME ‘ha_archive.so’

That’s all there is to it.

The blackhole, example, federated and innodb (beta) plugins are also available – you can view the list here.

UPDATE 15/07/10

This isn’t required any more (version 5.1.48-2) the Archive storage engine is now built in.

Eclipse PDT – code assist or PHP Manual not working

If you are new to Eclipse PDT and find that code assist or the PHP Manual (Shift+F2 or Open PHP Manual) are not working for a particular project, check that you have a file named .buildpath in the root of your project.

If there is nothing there, try creating a new project (File / New / PHP Project) grab the file from there and copy it into your existing project.

Alternatively just paste in the following:
<?xml version="1.0" encoding="UTF-8"?>
<buildpath>
<buildpathentry kind="src" path=""/>
<buildpathentry kind="con" path="org.eclipse.php.core.LANGUAGE"/>
</buildpath>

MySQL Transactions will automatically rollback if not committed

Just a quick note on this one, because although it seems obvious, I couldn’t find this explicitly mentioned anywhere in the MySQL manual entry for transaction syntax.

However if you issue an SQL ‘START TRANSACTION’ statement, anything you do after that will not affect the tables unless the ‘COMMIT’ statement is issued (assuming they are InnoDB tables). This is great because if your server crashed or you lost your connection to it, your data is protected.

Here’s an article from weberdev.com with more information: Using transactions in MySQL

Finding top level directory sizes with Linux

If you need to find out where the hard drive space on your Linux server has been taken up, here is a suggestion.

From the root directory if you use:

sudo du -h

You get an unmanageably long list of all the subdirectories on your system.
If you direct the output to a file however, you can use egrep to provide a useful summary, just showing the totals for the top level directories:

sudo du -h > ~/dirsize.txt
egrep ‘^[0-9.MKG]+[[:space:]]+./[a-z]+$’ dirsize.txt