| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
| Cc: | "Josh Berkus" <josh(at)agliodbs(dot)com>, "Pavan Deolasee" <pavan(at)enterprisedb(dot)com>, "Mark Kirkwood" <markir(at)paradise(dot)net(dot)nz>, "Gavin Sherry" <swm(at)alcove(dot)com(dot)au>, "Luke Lonergan" <llonergan(at)greenplum(dot)com>, "PGSQL Hackers" <pgsql-hackers(at)postgresql(dot)org>, "Doug Rady" <drady(at)greenplum(dot)com>, "Sherry Moore" <sherry(dot)moore(at)sun(dot)com> |
| Subject: | Re: Bug: Buffer cache is not scan resistant |
| Date: | 2007-03-05 20:18:47 |
| Message-ID: | 21794.1173125927@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
> Best way is to prove it though. Seems like not too much work to have a
> private ring data structure when the hint is enabled. The extra
> bookeeping is easily going to be outweighed by the reduction in mem->L2
> cache fetches. I'll do it tomorrow, if no other volunteers.
[ shrug... ] No one has yet proven to my satisfaction that L2 cache has
anything to do with this. The notion that you can read a new disk page
into a shared buffer and have that buffer still be live in the processor
cache is so obviously bogus that I think there must be some other effect
at work.
regards, tom lane
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