Re: New IndexAM API controlling index vacuum strategies

On Wed, Mar 17, 2021 at 11:23 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Attached the updated patch that can be applied on top of your v3 patches.

Some feedback on this:

* I think that we can afford to be very aggressive here, because we're
checking dynamically. And we're concerned about extremes only. So an
age of as high as 1 billion transactions seems like a better approach.
What do you think?

* I think that you need to remember that we have decided not to do any
more index vacuuming, rather than calling
check_index_cleanup_xid_limit() each time -- maybe store that
information in a state variable.

This seems like a good idea because we should try to avoid changing
back to index vacuuming having decided to skip it once. Also, we need
to refer to this in lazy_scan_heap(), so that we avoid index cleanup
having also avoided index vacuuming. This is like the INDEX_CLEANUP =
off case, which is also only for emergencies. It is not like the
SKIP_VACUUM_PAGES_RATIO case, which is just an optimization.

Thanks
-- 
Peter Geoghegan