Re: COALESCE and NULLIF semantics

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, pgsql-hackers(at)postgresql(dot)org, Sam Mason <sam(at)samason(dot)me(dot)uk>
Subject: Re: COALESCE and NULLIF semantics
Date: 2009-09-11 21:19:20
Message-ID: 1252703960.9975.89.camel@monkey-cat.sm.truviso.com
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On Fri, 2009-09-11 at 12:59 -0400, Tom Lane wrote:
> If so then ROW(NULL,NULL) would be
> indistinguishable from NULL and the semantic gripes seem to largely
> go away. It would be a problem for anyone who actually wanted to
> distinguish those two cases, but how much do we care?

Does that violate the standard?

To make that interpretation work I think you would need to say that
ROW(NULL,NULL) _is_ the null value, and you would have to allow things
like:

select 1 + row(null,null);

which seems strange to me.

Regards,
Jeff Davis

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