Re: Artificially increase TransactionID?

"Robert A. Klahn" <robert@kint.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