| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | "Sergey E(dot) Koposov" <math(at)sai(dot)msu(dot)ru>, Jim Nasby <jim(at)nasby(dot)net>, Greg Stark <stark(at)mit(dot)edu>, 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 07:01:27 |
| Message-ID: | CAM3SWZRw93mAn1wBo0-5Aca-YD1-YqZskECZus+t5_E2gjvhog@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Dec 10, 2013 at 10:34 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 11 December 2013 01:27, Sergey E. Koposov <math(at)sai(dot)msu(dot)ru> wrote:
>> For what it's worth.
>>
>> I'll quote Chaudhuri et al. first line from the abstract about the block
>> sampling.
>> "Block-level sampling is far more efficient than true uniform-random
>> sampling over a large database, but prone to significant errors if used to
>> create database statistics."
>
> This glosses over the point that both SQLServer and Oracle use this technique.
That seems like an unusual omission for Microsoft Research to have made.
I didn't read that paper, because undoubtedly it's all patented. But
before I figured that out, after finding it on Google randomly, I did
read the first couple of paragraphs, which more or less said "what
follows - the entire paper - is an explanation as to why it's okay
that we do block sampling".
--
Peter Geoghegan
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