Re: [PATCH] Support for foreign keys with arrays

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCH] Support for foreign keys with arrays
Date: 2011-11-17 05:44:54
Message-ID: 2334.1321508694@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> BTW, has anyone thought through whether this is a sane idea at all?
>> It seems to me to be full of cases that will require rather arbitrary
>> decisions, like whether ON DELETE CASCADE should involve deleting the
>> whole row or just one array element.

> One array element, presumably.

Um, why? One reasonable interpretation of an array reference is that
the row depends on *all* of the referenced pkeys. Also, if you do
delete one array element at a time, what do you do when the array
becomes empty --- delete the row, or not, and in each case what's your
semantic justification for that choice?

In short, "presumably" doesn't cut it here.

regards, tom lane

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