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EXPLAIN for Devel query log - #D7CX

By moshe weitzman - Posted on 02 February 2010

The query log feature of devel.module has faithfully served us since 2002, relatively unchanged. Since then, the web learned about AJAX and now devel for Drupal 7 finally gets with the times.

In the ops column of the screenshot above, you will see three ajax links titled P, A, E. Those stand for Placeholders, Arguments, and EXPLAIN. They work as follows:

  • Placeholders. This is the default presentation of a query. Here we see SQL with placeholders instead of values. This is the most compact representation.
  • Arguments. This link retrieves the same SQL replaces placeholders with actual values. This presentation is helpful for debugging and for copy/paste into you mysql editor for optimization.
  • EXPLAIN. This link shows the EXPLAIN output for the query. This is super helpful for optimizing any slow query.

Also, The far right column is helpful for knowing which slave server actually executed a given query (master/slave is a new feature of D7).

One of my goals here is to help module maintainers to upgrade and optimize their modules. Go #D7CX. Devel is well along in its pledge having released Alpha-1

Tags
Awesome!
Submitted by Bevan (not verified) on Tue, 02/02/2010 - 21:44.

This will be so useful! Thank you.

Whoa!
Submitted by Josh Koenig (not verified) on Tue, 02/02/2010 - 22:50.

That is superhot. Getting more people using EXPLAIN in development is a huge best-practice win. It's great to see devel.module continually adding these awesome new features! :)

When does it explain?
Submitted by Stewart Robinson (not verified) on Wed, 02/03/2010 - 08:32.

Moshe,

You say "The query log feature of devel.module has faithfully served us since 2002, relatively unchanged. Since then, the web learned about AJAX and now devel for Drupal 7 finally gets with the times."

I assume this means that the EXPLAIN is run when you click on it rather than during execution?

Yes, thats correct. When you
Submitted by moshe weitzman on Wed, 02/03/2010 - 13:56.

Yes, thats correct. When you click that link, an AJAX request is fired off to the server and the server returns a table of results. We don't try to run EXPLAIN for every query in real time.

Thanks Moshe :)
Submitted by Wim Leers (not verified) on Wed, 02/03/2010 - 13:11.

Yet another awesome Devel module feature :) Thanks Moshe!

This is great. Keep up the
Submitted by psynaptic (not verified) on Sat, 02/06/2010 - 21:34.

This is great. Keep up the good work :)

Meet the Experts

Moshe Weitzman

Moshe is one of the most senior and accomplished members of the Drupal community. He started committing code to Drupal in 2001. He is the second most prolific contributor in Drupal's history. Moshe's Certified to Rock score is 11 (highest - 5 others). View Moshe's Drupal resume. In addition his expertise with data migration, Moshe is the mainainer of the famous drush project and devel project.

Mike Ryan

Mike has given much to the Drupal community since first contributing in 2003. He's the wiz behind the Migrate and Table Wizard modules. He was also the original author of the Pathauto module, a terrific tool for automatically creating friendly URLs for pages and thus greatly improving SEO. Mike's given a lot to the Drupal community, and evidenced by his Certified to Rock score of 8