| From: | Jim Nasby <decibel(at)decibel(dot)org> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Luke Lonergan <LLonergan(at)greenplum(dot)com>, Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>, 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: | 2007-03-07 00:43:43 |
| Message-ID: | 4E324E75-2AF9-4F2F-A9A9-88248AEF205A@decibel.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Mar 6, 2007, at 10:56 AM, Jeff Davis wrote:
>> We also don't need an exact count, either. Perhaps there's some way
>> we could keep a counter or something...
>
> Exact count of what? The pages already in cache?
Yes. The idea being if you see there's 10k pages in cache, you can
likely start 9k pages behind the current scan point and still pick
everything up.
But this is nowhere near as useful as the bitmap idea, so I'd only
look at it if it's impossible to make the bitmaps work. And like
others have said, that should wait until there's at least a first-
generation patch that's going to make it into 8.3.
--
Jim Nasby jim(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
| From | Date | Subject | |
|---|---|---|---|
| Next Message | ITAGAKI Takahiro | 2007-03-07 01:56:04 | Re: Aggressive freezing in lazy-vacuum |
| Previous Message | Jim Nasby | 2007-03-07 00:38:44 | Re: Bug: Buffer cache is not scan resistant |