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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Stark <gsstark@mit.edu>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: Sun, 14 Feb 2010 12:11:39 -0500
Message-ID: <22295.1266167499@sss.pgh.pa.us> (raw)
In-Reply-To: <407d949e1002140731j85a4f97nc053ec1b0f3cc458@mail.gmail.com>
References: <4427a97a0912101235x3ade510blcc00d5ce9883c6b6@mail.gmail.com>
	<20100208030901.GA7407@alvh.no-ip.org>
	<603c8f071002072053w16897addtd52fcc4cf880df53@mail.gmail.com>
	<201002110327.35810.andres@anarazel.de>
	<603c8f071002120749o6a2e9e54h5cf21dc91d1790b9@mail.gmail.com>
	<407d949e1002140603v1c7515d7t697568a3865ac6fe@mail.gmail.com>
	<407d949e1002140731j85a4f97nc053ec1b0f3cc458@mail.gmail.com>

Greg Stark <gsstark@mit.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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