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Re: TOAST performance (was Re: [GENERAL] Delete Performance)

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: "P(dot)J(dot) \"Josh\" Rovero" <rovero(at)sonalysts(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: TOAST performance (was Re: [GENERAL] Delete Performance)
Date: 2001-12-20 22:00:57
Message-ID: 200112202200.fBKM0vx25436@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-hackers
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Is it because we take a snapshot of the page before we write it in case
> > we only write part of the page?
> 
> AFAIR, the partial-page-write problem is the entire reason for doing it.
> If we could be certain that writes to datafile pages were atomic, we'd
> not need this.
> 
> Of course we can't be certain of that.  But I'm wondering if there isn't
> a cheaper solution.

I have added these TODO items to summarize this discussion:

* Reduce number of pre-page WAL writes; they exist only to gaurd against
  partial page writes
* Turn off pre-page writes if fsync is disabled (?)

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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