From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: UPDATE SET (a,b,c) = (SELECT ...) versus rules |
Date: | 2014-06-14 19:45:08 |
Message-ID: | 20140614194508.GE6763@awork2.anarazel.de |
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Thread: | |
Lists: | pgsql-hackers |
Hi,
On 2014-06-14 15:35:33 -0400, Tom Lane wrote:
> Given that ON UPDATE rules are close to being a deprecated feature,
> it doesn't seem appropriate to work harder than this; and frankly
> I don't see how we could avoid multiple sub-select evaluations anyway,
> if the NEW references are in WHERE or other odd places.
>
> Another possible answer is to just throw a "not implemented" error;
> but that doesn't seem terribly helpful, and I think it wouldn't save
> a lot of code anyway.
I vote for throwing an error. This would make the rules about how rules
can be used safely even more confusing. I don't think anybody would be
helped by that. If somebody wrote a halfway sane ON UPDATE rule
(i.e. calling a function to do the dirty work) it wouldn't be sane
anymore if somebody starts to use the new syntax...
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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