| From: | Hannu Krosing <hannu(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)mit(dot)edu>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Peter Geoghegan <pg(at)heroku(dot)com>, Jim Nasby <jim(at)nasby(dot)net>, Josh Berkus <josh(at)agliodbs(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: ANALYZE sampling is too good |
| Date: | 2013-12-11 07:50:25 |
| Message-ID: | 52A81941.1080704@2ndQuadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 12/11/2013 01:44 AM, Greg Stark wrote:
> On Wed, Dec 11, 2013 at 12:40 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> When we select a block we should read all rows on that block, to help
>> identify the extent of clustering within the data.
> So how do you interpret the results of the sample read that way that
> doesn't introduce bias?
>
Initially/experimentally we could just compare it to our current approach :)
That is, implement *some* block sampling and then check it against what
we currently have. Then figure out the bad differences. Rinse. Repeat.
Cheers
--
Hannu Krosing
PostgreSQL Consultant
Performance, Scalability and High Availability
2ndQuadrant Nordic OÜ
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