| From: | Peter Geoghegan <peter(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Greg Stark <stark(at)mit(dot)edu>, Robert Haas <robertmhaas(at)gmail(dot)com>, "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu>, Greg Smith <greg(at)2ndquadrant(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Ants Aasma <ants(at)cybertec(dot)at>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Patch: add timing of buffer I/O requests |
| Date: | 2012-04-14 03:21:44 |
| Message-ID: | CAEYLb_U41=LUAdtump+sDF0C1XMmxh9CErRhfm0_cav7=167aQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 14 April 2012 03:01, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Realistically, I'm more worried about collisions due to inadequacies in
> the jumble calculation logic (Peter already pointed out some risk
> factors in that regard).
It's important to have a sense of proportion about the problem. The
worst thing that a collision can do is lead the DBA on a bit of a wild
goose chase. Importantly, collisions across databases and users are
impossible. I've always taken the view that aggregating query
statistics is a lossy process, and these kinds of problems seem like a
more than acceptable price to pay for low-overhead dynamic query
statistics .
--
Peter Geoghegan http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services
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