| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | "J(dot) R(dot) Nield" <jrnield(at)usol(dot)com> |
| Cc: | Curt Sampson <cjs(at)cynic(dot)net>, Michael Loftis <mloftis(at)wgops(dot)com>, mlw <markw(at)mohawksoft(dot)com>, PostgreSQL Hacker <pgsql-hackers(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: Index Scans become Seq Scans after VACUUM ANALYSE |
| Date: | 2002-06-22 23:17:11 |
| Message-ID: | 200206222317.g5MNHBn23427@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
J. R. Nield wrote:
> One other point:
>
> Page pre-image logging is fundamentally the same as what Jim Grey's
> book[1] would call "careful writes". I don't believe they should be in
> the XLOG, because we never need to keep the pre-images after we're sure
> the buffer has made it to the disk. Instead, we should have the buffer
> IO routines implement ping-pong writes of some kind if we want
> protection from partial writes.
Ping-pong writes to where? We have to fsync, and rather than fsync that
area and WAL, we just do WAL. Not sure about a win there.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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