Re: win32 performance - fsync question

From: "Zeugswetter Andreas DAZ SD" <ZeugswetterA(at)spardat(dot)at>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Magnus Hagander" <mha(at)sollentuna(dot)net>
Cc: <pgsql-hackers(at)postgresql(dot)org>, "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
Subject: Re: win32 performance - fsync question
Date: 2005-02-18 12:02:32
Message-ID: 46C15C39FEB2C44BA555E356FBCD6FA40184D2FF@m0114.s-mxs.net
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> One point that I no longer recall the reasoning behind is that xlog.c
> doesn't think O_SYNC is a preferable default over fsync.

For larger (>8k) transactions O_SYNC|O_DIRECT is only good with the recent
pending patch to group WAL writes together. The fsync method gives the OS a
chance to do the grouping. (Of course it does not matter if you have small
tx < 8k WAL)

Andreas

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