| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Mike Nolan <nolan(at)gw(dot)tssi(dot)com> |
| Cc: | gwood(at)ewebengine(dot)com (Gregory Wood), pgsql-general(at)postgresql(dot)org (pgsql general list) |
| Subject: | Re: Trigger loop question |
| Date: | 2004-03-16 04:42:14 |
| Message-ID: | 12928.1079412134@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Mike Nolan <nolan(at)gw(dot)tssi(dot)com> writes:
> Yes it does. OK, that means Tom's original suggestion of checking
> the other table for the same value before updating it should prevent
> an infinite loop, providing that's done from a pair of 'after update'
> triggers, using the NEW.column entries in the triggered table to update
> the other table.
Actually, I wasn't thinking very clearly. The easiest way to break
the loop is to avoid updating the other table when OLD.x = NEW.x
in the trigger's arguments. The other way requires a rather-redundant
SELECT to see what is in the other table.
regards, tom lane
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