| 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 |
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| Lists: | pgsql-docs pgsql-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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