"Matthew T. O'Connor" <matthew@zeut.net> writes:
> I'm not sure what you are saying here, are you now saying that partial
> vacuum won't work for autovac? Or are you saying that saving state as
> Jim is describing above won't work?
I'm saying that I don't like the idea of trying to "stop on a dime" by
saving the current contents of vacuum's dead-TID array to disk with the
idea that we can trust those values 100% later. Saving the array is
expensive both in runtime and code complexity, and I don't believe we
can trust it later --- at least not without even more expensive-and-
complex measures, such as WAL-logging every such save :-(
I'm for stopping only after completing an index-cleaning pass, at the
point where we empty the dead-TID array anyway. If you really have to
have "stop on a dime", just kill -INT the process, accepting that you
will have to redo your heap scan since the last restart point.
regards, tom lane