Re: Checkpoint cost, looks like it is WAL/CRC

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Greg Stark <gsstark(at)mit(dot)edu>, Russell Smith <mr-russ(at)pws(dot)com(dot)au>, josh(at)agliodbs(dot)com, Postgres Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Checkpoint cost, looks like it is WAL/CRC
Date: 2005-07-07 15:59:41
Message-ID: 200507071559.j67Fxfa15633@candle.pha.pa.us
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Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom Lane wrote:
> >> The point here is that fsync-off is only realistic for development
> >> or playpen installations. You don't turn it off in a production
> >> machine, and I can't see that you'd turn off the full-page-write
> >> option either. So we have not solved anyone's performance problem.
>
> > Yes, this is basically another fsync-like option that isn't for
> > production usage in most cases. Sad but true.
>
> Just to make my position perfectly clear: I don't want to see this
> option shipped in 8.1. It's reasonable to have it in there for now
> as an aid to our performance investigations, but I don't see that it
> has any value for production.

Well, this is the first I am hearing that, and of course your position
is just one vote.

One idea would be to just tie its behavior directly to fsync and remove
the option completely (that was the original TODO), or we can adjust it
so it doesn't have the same risks as fsync, or the same lack of failure
reporting as fsync.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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