From: chester c young <chestercyoung@yahoo.com>
To: josh@agliodbs.com
To: pgsql-sql@postgresql.org
Subject: Re: Is there any way to stop triggers from cycling?
Date: Wed, 8 Mar 2006 15:04:18 -0800 (PST)
Message-ID: <20060308230419.53923.qmail@web54308.mail.yahoo.com> (raw)
In-Reply-To: <200603081358.25185.josh@agliodbs.com>
trying to do this exlusively in triggers is a forray into folly.
take advantage of "instead of" or "do also" rules to create a compound
statement before your triggers do their work. (in terms of maintenance
and sanity, it's best if a trigger touches only its own record.)
as a handsweep example:
create view tree_v as select * from tree;
grant select, insert, update on tree_v to public;
create or replace rule 'tree_update' as
on update
to tree_v
do instead(
--
update tree set seq = seq+1
where old.pnt=new.pnt and old.seq<new.seq-1
and pnt = old.pnt and seq between old.seq and new.neq;
--
update tree set set = new.seq
where old.pnt=new.pnt and old.seq != new.seq
and pnt = old.pnt and seq = new.seq;
);
note two conditions on the where clause: first is rule when to do it,
and second is what record to do it on.
you might not need the intermediate view, but I always use a view
between my app and the table - for reasons like this and many, many
others.
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To: pgsql-sql@postgresql.org
Cc: chestercyoung@yahoo.com, josh@agliodbs.com
Subject: Re: Is there any way to stop triggers from cycling?
In-Reply-To: <20060308230419.53923.qmail@web54308.mail.yahoo.com>
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