| From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: auto_explain sample rate |
| Date: | 2015-06-03 13:00:25 |
| Message-ID: | CAMsr+YFXQ+G_9MHfoRvVo83knPbcaCCS7+P+dft_qJY45cFeEQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 3 June 2015 at 20:04, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2015-06-03 18:54:24 +0800, Craig Ringer wrote:
> > OK, here we go.
>
> Hm. Wouldn't random sampling be better than what you do? If your queries
> have a pattern to them (e.g. you always issue the same 10 queries in
> succession), this will possibly only show a subset of the queries.
>
> I think a formulation in fraction (i.e. a float between 0 and 1) will
> also be easier to understand.
Could be, yeah. I was thinking about the cost of generating a random each
time, but it's going to vanish in the noise compared to the rest of the
costs in query execution.
---
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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