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Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: 2010-02-14 17:11:39
Message-ID: 22295.1266167499@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
Greg Stark <gsstark(at)mit(dot)edu> writes:
> So I think we have a bigger problem than just copydir.c. It seems to
> me we should be fsyncing the table space data directories on every
> checkpoint.

Is there any evidence that anyone anywhere has ever lost data because
of a lack of directory fsyncs?  I sure don't recall any bug reports
that seem to match that theory.

It seems to me that we're talking about a huge hit in both code
complexity and performance to deal with a problem that doesn't actually
occur in the field; and which furthermore is trivially solved on any
modern filesystem by choosing the right filesystem options.  Why don't
we just document those options, instead?

			regards, tom lane

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