Re: BUG #13002: VACUUM to prevent wraparound blocks TRUNCATE

Jeff Janes <jeff.janes@gmail.com> writes:
> Right now we declare it an emergency that some guy needs to change his oil,
> shutdown half the traffic in the city during the "emergency", declare that
> all the emergency vehicles responding to this emergency are only allowed to
> move at 1/3 the speed limit, and make it illegal (or at least ineffective)
> for anyone to change their oil calmly and preemptively.

We could do without hyperbolic and wholly misleading analogies.  (In this
one, for example, you're omitting that the guy causing the problem is a
couple years overdue to have changed his oil, and will blow a gasket and
block the entire highway if he drives further.)

Getting back to the case at hand, I don't think that making an exception
for TRUNCATE would be a good idea even if there were no technical
obstacles.  It's perfectly possible for a TRUNCATE to be rolled back; so
if the TRUNCATE were to kick an emergency autovac off the table lock and
then fail, you would end up with no improvement in the situation at all.

            regards, tom lane