Re: Big 7.4 items

From: Neil Conway <neilc(at)samurai(dot)com>
To: Jan Wieck <JanWieck(at)Yahoo(dot)com>
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, shridhar_daithankar(at)persistent(dot)co(dot)in, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Big 7.4 items
Date: 2002-12-13 23:38:33
Message-ID: 1039822713.1397.35.camel@tokyo
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On Fri, 2002-12-13 at 13:36, Jan Wieck wrote:
> But you cannot use the result of such a SELECT to update anything. So
> you can only phase out complete read only transaction to the slaves.
> Requires support from the application since the load balancing system
> cannot know automatically what will be a read only transaction and what
> not.

Interesting -- SQL contains the concept of "read only" and "read write"
transactions (the default is RW). If we implemented that (which
shouldn't be too difficult[1]), it might make differentiating between
classes of transactions a little easier. Client applications would still
need to be modified, but not nearly as much.

Does this sound like it's worth doing?

[1] -- AFAICS, the only tricky implementation detail is deciding exactly
which database operations are "writes". Does nextval() count, for
example?

Cheers,

Neil
--
Neil Conway <neilc(at)samurai(dot)com> || PGP Key ID: DB3C29FC

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