Re: Artificially increase TransactionID?

"Robert A. Klahn" <robert(at)kint(dot)org> writes:
> I am interested in increasing the PostgreSQL TransactionID, as part
> of testing a (yet another) replication system that I am working on.
> (http://bruce.codehaus.org/ for the interested). I would like to test
> what happens when the transactionID crosses 2^31 and when it wraps
> around at 2^32-1. Other than running "select now()" 2^31 times, is
> there a practical way to raise the transactionID by large amounts?

Shut down postmaster, use pg_resetxlog to set NextXID to whatever you
want, restart and test. You might need to artificially create pg_clog
and pg_subtrans segments matching the chosen starting point, but other
than that there's not a lot of memory of latest XID in the system.

Bumping it by more than 2G-less-reasonable-safety-margin is unfair of
course ...

regards, tom lane