From: | "Daniel Verite" <daniel(at)manitou-mail(dot)org> |
---|---|
To: | "Thiemo Kellner, NHC Barhufpflege" <thiemo(dot)kellner(at)gelassene-pferde(dot)biz> |
Cc: | "pgsql-general" <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Dynamic PL/pgSQL select query: value association propblem |
Date: | 2018-02-16 13:56:30 |
Message-ID: | a2e5e1ab-755d-4854-8c5b-5c5c2b24e5b6@manitou-mail.org |
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Lists: | pgsql-general |
Thiemo Kellner, NHC Barhufpflege wrote:
> > Why you don't create query like
> >
> > EXECUTE 'SELECT xxx FROM TAB WHERE A = $1.x AND B = $1.y' USING NEW;
>
> I shall try. This would be the direct way, but I doubt the placeholder
> $1 can be a record.
It could be written without refering to any individual column:
IF EXISTS (select 1 from tablename
where tablename.* is not distinct from NEW)
THEN
-- do something
END IF;
But since the select cannot see not-yet-committed changes from other
sessions, such a trigger cannot reliably detect duplicates, unless
you make sure that there are no concurrent writes to the table.
Best regards,
--
Daniel Vérité
PostgreSQL-powered mailer: http://www.manitou-mail.org
Twitter: @DanielVerite
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