| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>, Isaac Morland <isaac(dot)morland(at)gmail(dot)com>, Eugen Konkov <kes-kes(at)yandex(dot)ru>, David Fetter <david(at)fetter(dot)org>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Proposition to use '==' as synonym for 'IS NOT DISTINCT FROM' |
| Date: | 2019-10-28 15:38:09 |
| Message-ID: | 20191028153809.6nhm2xkzq3ifryty@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2019-10-28 10:41:31 -0400, Robert Haas wrote:
> I mean, do we have to break the extensions? If we just added ==
> operators that behaved like IS NOT DISTINCT FROM to each datatype, why
> would anything get broken? I mean, if someone out there has a
> ==(int4,int4) operator, that would get broken, but what's the evidence
> that any such thing exists, or that its semantics are any different
> from what we're talking about?
>
> If we added == as a magic parser shortcut for IS NOT DISTINCT FROM,
> that would be more likely to break things, because it would affect
> every conceivable data type. I don't think that's a great idea, but
Without some magic, the amount of repetitive changes, the likelihood of
inconsistencies, and the reduced information about semantic meaning to
the planner (it'd not be a btree op anymore!), all seem to argue against
adding such an operator.
Greetings,
Andres Freund
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