From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Dimitri Fontaine <dfontaine@hi-media.com>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: PostgreSQL as a local in-memory cache
Date: Tue, 29 Jun 2010 13:27:34 -0400
Message-ID: <20972.1277832454@sss.pgh.pa.us> (raw)
In-Reply-To: <201006291719.o5THJeK29759@momjian.us>
References: <201006291719.o5THJeK29759@momjian.us>
Bruce Momjian <bruce@momjian.us> writes:
>>> I asked on IRC and was told it is true, and looking at the C code it
>>> looks true. ?What synchronous_commit = false does is to delay writing
>>> the wal buffers to disk and fsyncing them, not just fsync, which is
>>> where the commit loss due to db process crash comes from.
>> Ah, I see. Thanks.
> I am personally surprised it was designed that way; I thought we would
> just delay fsync.
That would require writing and syncing to be separable actions. If
you're using O_SYNC or similar, they aren't.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, bruce@momjian.us, robertmhaas@gmail.com, dfontaine@hi-media.com, josh@agliodbs.com
Subject: Re: PostgreSQL as a local in-memory cache
In-Reply-To: <20972.1277832454@sss.pgh.pa.us>
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