Re: Revisiting default_statistics_target - Mailing list pgsql-hackers

From Greg Smith
Subject Re: Revisiting default_statistics_target
Date
Msg-id alpine.GSO.2.01.0905221545300.12223@westnet.com
Whole thread Raw
In response to Re: Revisiting default_statistics_target  ("Greg Sabino Mullane" <greg@turnstep.com>)
Responses Re: Revisiting default_statistics_target  (Greg Stark <greg.stark@enterprisedb.com>)
List pgsql-hackers
On Fri, 22 May 2009, Greg Sabino Mullane wrote:

>> The bump from 10 to 100 was supported by microbenchmarks that suggested it
>> would be tolerable.
>
> No, the 10 to 100 was supported by years of people working in the field who
> routinely did that adjustment (and >100) and saw great gains.

No one is suggesting the increase isn't important to people running many 
common workloads.  The question the smaller benchmarks tried to answer is 
whether it was likely to detune anything else as a penalty for improving 
that situation.  The comments you made here can get turned right around at 
you:  if increasing the value in the field is sufficient to help out those 
that need it, why should the project at large accept any significant 
penalty that could apply to everyone just to help that subset?

Would you be happy with 8.4 going out the door if there really turns out 
to be a 15% penalty for other use cases by this change?  That's a PR 
nightmare waiting to happen, and the main reason I wanted to bring this up 
here with some additional details as soon as Jignesh's slides went 
public--so everyone here is aware of what's going on before this bit of 
news gets picked up anywhere else.

Hopefully whatever is happening to dbt2 will turn out to be a quirk not 
worth worrying about.  What if it turns out to be repeatable and expected 
to impact people in the field though?  I hope you'd recognize that your 
use case is no more privileged to trump other people's than the changes 
that would be good for DW users, but not anyone else, that you were just 
making critical comments about.

Anyway, thanks to Stephen for concisely clarifying the position I was 
trying to present here, which is quite different from the one you were 
arguing against.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD


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