Re: INSERT...ON DUPLICATE KEY LOCK FOR UPDATE

From: Jim Nasby <jim(at)nasby(dot)net>
To: Peter Geoghegan <pg(at)heroku(dot)com>
Cc: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: INSERT...ON DUPLICATE KEY LOCK FOR UPDATE
Date: 2014-01-11 01:02:35
Message-ID: 52D0982B.7060901@nasby.net
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On 1/10/14, 6:51 PM, Peter Geoghegan wrote:
> On Fri, Jan 10, 2014 at 4:09 PM, Jim Nasby<jim(at)nasby(dot)net> wrote:
>> >Well, the usual example for exclusion constraints is resource scheduling
>> >(ie: scheduling what room a class will be held in). In that context is it
>> >hard to believe that you might want to MERGE a set of new classroom
>> >assignments in?
> So you schedule a class that clashes with 3 other classes, and you
> want to update all 3 rows/classes with details from your one row
> proposed for insertion?

Nuts, I was misunderstanding the scenario. I thought this was simply going to violate exclusion constraints.

I see what you're saying now, and I'm not coming up with a scenario either. Perhaps Jeff Davis could, since he created them... if he can't then I'd say we're safe ignoring that aspect.
--
Jim C. Nasby, Data Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net

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