Re: a verbose option for autovacuum

On Thu, Mar 18, 2021 at 11:30:46PM +0900, Masahiko Sawada wrote:
> Sorry, I attached the wrong version patch. So attached the right one.

Thanks.  I have been hacking aon that, and I think that we could do
more in terms of integration of the index stats into LVRelStats to
help with debugging issues, mainly, but also to open the door at
allowing autovacuum to use the parallel path in the future.  Hence,
for consistency, I think that we should change the following things in
LVRelStats:
- Add the number of indexes.  It looks rather unusual to not track
down the number of indexes directly in the structure anyway, as the
stats array gets added there.
- Add all the index names, for parallel and non-parallel mode.
- Replace the index name in the error callback by an index number,
pointing back to its location in indstats and indnames.

As lazy_vacuum_index() requires the index number to be set internally
to it, this means that we need to pass it down across
vacuum_indexes_leader(), lazy_parallel_vacuum_indexes(), but that
seems like an acceptable compromise to me for now.  I think that it
would be good to tighten a bit more the relationship between the index
stats in the DSM for the parallel case and the ones in local memory,
but what we have here looks enough to me so we could figure out that
as a future step.

Sawada-san, what do you think?  Attached is the patch I have finished
with.
--
Michael