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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-performance@postgresql.org, Josh Berkus <josh@agliodbs.com>
Cc: Greg Smith <greg@2ndquadrant.com>
Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
Date: Tue, 16 Nov 2010 20:17:43 -0500
Message-ID: <11392.1289956663@sss.pgh.pa.us> (raw)
In-Reply-To: <11113.1289955868@sss.pgh.pa.us>
References: <AANLkTi=n3zxiLNFhbpiN=JPQPwB=BhXf9iepw1KOEs8U@mail.gmail.com>
	<201011170130.10720.andres@anarazel.de>
	<10822.1289955088@sss.pgh.pa.us>
	<201011170201.24782.andres@anarazel.de>
	<11113.1289955868@sss.pgh.pa.us>

I wrote:
> The fsync is associated with the write, which is not done with insert
> lock held.  We're not quite that dumb.

But wait --- are you thinking of the call path where a write (and
possible fsync) is forced during AdvanceXLInsertBuffer because there's
no WAL buffer space left?  If so, that's *exactly* the scenario that
can be expected to be less common with more buffer space.

			regards, tom lane



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  Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
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