Date: Tue, 22 Jul 2003 12:06:56 -0400 (EDT) From: David Miller <small@d.sparks.net> To: Dan Langille <dan@langille.org> Cc: Jason Stone <freebsd-performance@dfmm.org> Subject: Re: Tuning for PostGreSQL Database Message-ID: <Pine.BSF.4.21.0307221201120.62967-100000@search.sparks.net> In-Reply-To: <3F1D2208.2124.52B03E6A@localhost>
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On Tue, 22 Jul 2003, Dan Langille wrote: > On 21 Jul 2003 at 20:35, Jason Stone wrote: > > > I feel like this is an extremely important point. If softupdates changes > > the semantics of sync(2)/fsync(2), then it absolutely has to be off for a > > postgresql server because postgresql counts on fsync in order to make its > > durability guarantees. > > If this means all FreeBSD-PostgreSQL users need to change their > setup, we need to do something ASAP. I'd first recommend getting the > confirmation from the PostgreSQL team, then adjusting the PostgreSQL > documenation and the FreeBSD port. If softupdates breaks the semantics of sync/fsync it affects a lot more than postgres, it affects every application that manages data on its own. Every other database that doesn't do raw IO would seem to be affected, for example. Before we go off half-cocked, can anyone confirm that softupdates actually does this - reorders/delays sync/fsync - on writes within a file? I had the impression it worked on meta data about files (directory structures) rather than the data within the file itself. --- David
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