explain.depesz.com version 2.0

Thanks to enormous work done by Łukasz ‘metys' Lewandowski, explain.depesz.com page is no longer “desiged by depesz" (which is a code for “ugly as hell"), but is nice, and good looking.

If you like it, please do send some thank you note to Łukasz – he blogs in Polish, but he reads and understands English too.

Change is not only skin deep. The whole site has been rewritten, and uses now Mojolicious web framework instead of Catalyst.

This change should be a welcome surprise to anyone willing to setup their own copy of the site for top-secret plans from their company – mostly because number of dependencies dropped significantly.

All in all – have fun, and thanks for using the site.

Two years of explain.depesz.com

First of all – just today I committed patch for Pg::Explain – which is the workhorse behind explain.depesz.com.

This patch fixes calculation of exclusive time for explain nodes, and the best thing about it is – I didn't write it. It's full patch provided by someone else – Filip Rembiałkowski – my former colleague, friend, and PostgreSQL DBA (not olny PG!).

This is (as far as I recall) first patch that was provided to me for this library, and I'm really grateful for the contribution.

New version of Pg::Explain will hit CPAN mirrors shortly (it's already uploaded, now we're waiting for CPAN mirrors to get it).

When I was updating it, I checked state of database. And I learned that explain.depesz.com is over 2 years now! Some stats follow.

Continue reading Two years of explain.depesz.com

explain.depesz.com – stats after a year

I just checked, and apparently explain.depesz.com is online for over a year now. First plans was added on 2008-12-04 13:20:43+01.

Since then there have been 3602 plans added, 770 of them were set to be private (not displayed on previous explains page.

Longest plan has 2267194 characters (yes, 2.2 megabytes of explain analyze output!), but it's not public, so I can't tell you the url. Longest public plan is this monstrosity, which (while being only explain output, not explain analyze) has 503585 characters.

During this time, there have been 61 days that nobody added any plan on (perhaps problems with software?).

The most heavily used day was 23rd of June 2009, when 71 new plans have been added (4 private).

Thank you all for using it. I hope you find it useful, and I promise, that one day, I will finally sit down, and add all long-due features (like work with new explain formats, fixing some output glitches, stats of used objects per plan).

If you'd like to take a peek at how it works – source of explain.depesz.com is always available.

Waiting for 8.5 – buffers info for explain

Today small, but (at least for me) really useful patch. Committed on 15th of December by Robert Haas, and written by Itagaki Takahiro, this patch does:

Log Message:
Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.
This patch also removes buffer-usage statistics from the track_counts
output, since this (or the global server statistics) is deemed to be a better
interface to this information.
Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.

Continue reading Waiting for 8.5 – buffers info for explain

Waiting for 8.5 – Machine readable EXPLAIN

After very long discussions, on 10th of August, Tom Lane committed patch by Robert Haas:

Log Message:
Extend EXPLAIN to support output in XML or JSON format.
There are probably still some adjustments to be made in the details
of the output, but this gets the basic structure in place.
Robert Haas

Continue reading Waiting for 8.5 – Machine readable EXPLAIN

explain.depesz.com – update

I just updated explain.depesz.com with 2 new interface features:

  • When you put mouse cursor over node, it will mark direct child nodes with
  • When you click on node, all child nodes (even indirect) will be hidden, and the node you clicked on will be marked with

Both features are directed towards people who analyze longer plans – ability to hide parts or just visually see what the Nested Loop is calling in 2nd stage greatly helps me see the flow of query – you can test it, for example, here.

By the way – BIG THANK YOU for Metys for help on it (well, actually, for doing it).