Posted on in Programming
This will just be a short reminder. If you're planning to create multiple-column indexes in MySQL, remember that the order of the columns matters. As the MySQL documentation points out, any "leftmost prefix of the index can be used." This means that the index can be used for any number …
Posted on in System Administration
We ran across the following error on a MySQL slave server recent:
mysql> SHOW SLAVE STATUS \G
<snip>
Last_Error: Query caused different errors on master and slave. Error on master: 'Deadlock found when trying to get lock; try restarting transaction' (1213), Error on slave: 'no error' (0). Default database: '<database_name …Posted on in Programming
If you need to debug what queries your WordPress site is making, try adding the
following PHP to your theme:
<?php
foreach ( $wpdb->queries as $query ) {
echo "$query[0]<br />";
}
?>
For this code to work, you need to add the following line to wp-config.php:
define('SAVEQUERIES', true);
After that …
Posted on in voice
I hate losing useful SQL queries, so I tend to save them. Ever so often, I stumble across a file of queries from some work I was doing months ago. The following two queries are just such a case. I was analyzing some call data for a call center that …
Posted on in Programming
I'm writing this post for two reasons:
SELECT DISTINCT().Recently, I was working on a project written in Ruby with ActiveRecord that …
Posted on in Programming
I was recently helping a developer with some SQL optimizations in Ruby. The developer was using Active Record, and (until now) my Active Record experience has been pretty minimal.
One thing that was really driving me bonkers was how to get Active Record to print out the queries it was …
