Tag: postgresql

Bloat removal without table swapping

Some time ago I wrote about my favorite method of bloat removal. Around one year earlier, I wrote about another idea for bloat removal. This older idea was great – it didn't involve usage of triggers, overhead on all writes, table swapping. It had just one small, tiny, minuscule little issue. It was unbearably slow.

My idea was explored by Nathan Thom, but his blogpost disappeared.

Recently, Sergey Konoplev wrote to me about his tool, that he wrote using the same idea – updating rows to move them to other pages. So I decided that I have to check it.

Continue reading Bloat removal without table swapping

What is the overhead of logging?

update at the end of the post!

There obviously is one – after all, logging information has to be more expensive than not logging it. But how big is it? And more importantly, what is the difference between logging to stderr/file, csvlog and syslog? And what about syslog to remote machine?

Let's see.

Continue reading What is the overhead of logging?

Pick a task to work on

There is new blogpost on this subject!

There are cases where system stores list of things to do, and then there are some worker processes that check the list, pick something to work on, do it, and remove from the list.

Proper solution is to use some kind of queuing system. There is even PgQ which works withing PostgreSQL, but some people are not happy with it, as it requires compilation and installation. So they just use plain selects.

Will that work OK?

Continue reading Pick a task to work on

Waiting for 9.4 – WITH CHECK OPTION support for auto-updatable VIEWs

On 18th of July, Stephen Frost committed patch:

WITH CHECK OPTION support for auto-updatable VIEWs
 
For simple views which are automatically updatable, this patch allows
the user to specify what level of checking should be done on records
being inserted or updated.  For 'LOCAL CHECK', new tuples are validated
against the conditionals of the view they are being inserted into, while
for 'CASCADED CHECK' the new tuples are validated against the
conditionals for all views involved (from the top down).
 
This option is part of the SQL specification.
 
Dean Rasheed, reviewed by Pavel Stehule

Continue reading Waiting for 9.4 – WITH CHECK OPTION support for auto-updatable VIEWs

Waiting for 9.4 – Add SQL Standard WITH ORDINALITY support for UNNEST (and any other SRF)

On 29th of July, Greg Stark committed patch:

Add SQL Standard WITH ORDINALITY support for UNNEST (and any other SRF)
 
Author: Andrew Gierth, David Fetter
Reviewers: Dean Rasheed, Jeevan Chalke, Stephen Frost

Continue reading Waiting for 9.4 – Add SQL Standard WITH ORDINALITY support for UNNEST (and any other SRF)