Re: using disable-triggers in pg_dump

Nick Fankhauser - Doxpop wrote:
> Hi-
>
> One of our processes requires merging data from a staging database into a
> production database. I'd like to do this without taking the production
> database off-line, but I'm running into a problem with triggers.
>
> One of the tables is populated and maintained solely by triggers set up on
> three other tables, so as those tables are being copied into the production
> database, many triggers are running, thus slowing the process considerably.
> Since the data created by the triggers already exists in this table in the
> database to be merged, if I could copy all of the data in with the triggers
> off, the process would be much faster and the end result identical.
>
> However, I need those triggers on to handle other updates & inserts in the
> production database unless it is taken off-line for duration of the merge
> process.
>
> I've noted the --disable-triggers option for pg_dump, but it appears that
> this option would shut off the triggers for all sessions, not just the
> session in which I am doing the copy.
>
> The command that pg_dump generates looks like this:
> UPDATE pg_catalog.pg_class SET reltriggers = 0 WHERE oid =
> 'court_config'::pg_catalog.regclass;
>
> Can someone confirm that this is indeed affecting the database for all
> sessions and if so, suggest a way to turn off the triggers just for the
> session doing the data copy?

One trick I have heard about is starting a multi-statement transaction,
turning of triggers, which will only be seen by that transaction, do
some work, reenable the triggers, then commit the transaction.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073