launchpad-dev team mailing list archive

[Gary Poster <gary.poster@xxxxxxxxxxxxx>]

Cool, thank you Stuart.

I've linked the incident report to the bug.

Gary


On Aug 24, 2011, at 11:36 PM, Stuart Bishop wrote:

> On Thu, Aug 25, 2011 at 2:48 AM, Gary Poster <gary.poster@xxxxxxxxxxxxx> wrote:
>> Hi Stuart.  When working on https://wiki.canonical.com/IncidentReports/2011-08-19-LP-confused-query-plan-degraded-performance , you noted that we should increase our Postgres statistics targets to make similar glitches less likely.
>> 
>> Am I right in assuming that this means increasing the frequency of updating the statistics targets?  What can we do to make this happen?  Does it have any downsides?  Should I file a bug for it, or make some other future-planning action?
> 
> It means that when PostgreSQL generates statistics for a table for the
> query planner to use, it samples more rows. This makes ANALYZE take
> longer, but no problems there since it is a background task and we
> have spare capacity. The more rows you sample, the less likely you are
> to get an anomalous sample.
> 
> I've added this to my list and opened
> https://bugs.launchpad.net/launchpad/+bug/833502 if people want to
> track or link to it.
> 
> 
> 
> -- 
> Stuart Bishop <stuart@xxxxxxxxxxxxxxxx>
> http://www.stuartbishop.net/