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Re: special integrity constraints

From: Bruno Wolff III <bruno(at)wolff(dot)to>
To: Erik Thiele <erik(at)thiele-hydraulik(dot)de>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: special integrity constraints
Date: 2004-03-22 15:12:11
Message-ID: 20040322151211.GA2962@wolff.to (view raw or flat)
Thread:
Lists: pgsql-docspgsql-sql
On Mon, Mar 22, 2004 at 14:10:42 +0100,
  Erik Thiele <erik(at)thiele-hydraulik(dot)de> wrote:
> 
> it means (((count_rows(a)+count_rows(b)) modulo 2) == 0)

OK, that means my FK suggestion won't help. The other suggestion about
putting triggers on "a" and "b" to update a count in another table
that has a deferred check constraint on it may be your best bet.
This will be a source of contention, but that may or may not be all
that important depending on how often you are updating "a" and "b".

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