Re: do only critical work during single-user vacuum?

On 12/9/21, 5:27 PM, "Peter Geoghegan"  wrote:
> I imagine that this new function (to handle maintenance tasks in the
> event of a wraparound emergency) would output information about its
> progress. For example, it would make an up-front decision about which
> tables needed to be vacuumed in order for the current DB's
> datfrozenxid to be sufficiently new, before it started anything (with
> handling for edge-cases with many tables, perhaps). It might also show
> the size of each table, and show another line for each table that has
> been processed so far, as a rudimentary progress indicator.

I like the idea of having a built-in function that does the bare
minimum to resolve wraparound emergencies, and I think providing some
sort of simple progress indicator (even if rudimentary) would be very
useful.  I imagine the decision logic could be pretty simple.  If
we're only interested in getting the cluster out of a wraparound
emergency, we can probably just look for all tables with an age over
~2B.

Nathan