Re: Check constraints on non-immutable keys

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: Magnus Hagander <magnus(at)hagander(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Check constraints on non-immutable keys
Date: 2010-06-30 22:57:50
Message-ID: 19277.1277938670@sss.pgh.pa.us
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Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> <kibo>
> "The <search condition> shall simply contain a <boolean value
> expression> that is retrospectively deterministic."

> This is then defined in a rather complex manner that ends up disallowing
> col > now() but allowing col < now().
> </kibo>

Oh, cute. Seems to have been added in SQL:2003. I guess somebody
nagged them about wanting to be able to write CHECK(col <= now()).
The detailed definition is amazingly laborious and yet limited, though,
as it basically doesn't address the problem except for that specific
case and close relatives.

regards, tom lane

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