Re: SSI patch version 14

From: Dan Ports <drkp(at)csail(dot)mit(dot)edu>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, simon(at)2ndQuadrant(dot)com, markus(at)bluegap(dot)ch, pgsql-hackers(at)postgresql(dot)org
Subject: Re: SSI patch version 14
Date: 2011-02-08 15:40:01
Message-ID: 20110208154001.GW9421@csail.mit.edu
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On Tue, Feb 08, 2011 at 11:25:34AM +0200, Heikki Linnakangas wrote:
> On 08.02.2011 10:43, Kevin Grittner wrote:
> > I see that at least three BuildFarm critters don't have UINT64_MAX
> > defined.
>
> I guess we'll have to just #define it ourselves. Or could we just pick
> another magic value, do we actually rely on InvalidSerCommitSeqno being
> higher than all other values anywhere?

As far as I know we don't specifically rely on that anywhere, and
indeed I did have it #defined to 1 at one point (with the other
constants adjusted to match) and I don't recall any problems. But given
that we most often use InvalidSerCommitSeqNo to mean "not committed
yet", it made more sense to set it to UINT64_MAX so that if a
comparison did sneak in it would do the right thing.

I did dust off a copy of the ANSI standard at the time, and it was
pretty explicit that UINT64_MAX is supposed to be defined in <stdint.h>.
But that may just be a C99 requirement (I didn't have an older copy of
the standard), and it's obviously no guarantee that it actually is
defined.

Dan

--
Dan R. K. Ports MIT CSAIL http://drkp.net/

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