On 2020-May-06, Peter Geoghegan wrote:
> Also, do we really want to skip summarization of BRIN indexes? This
> cleanup is rather dissimilar to the cleanup that takes place in most
> other AMs -- it isn't really that related to garbage collection (BRIN
> is rather unique in this respect). I think that BRIN might be an
> inappropriate target for "index_cleanup off" VACUUMs for that reason.
>
> See the explanation of how this takes place from the docs:
> https://www.postgresql.org/docs/devel/brin-intro.html#BRIN-OPERATION
Good question. I agree that BRIN summarization is not at all related to
what other index AMs do during the cleanup phase. However, if the
index_cleanup feature is there to make it faster to process a table
that's nearing wraparound hazards (or at least the warnings), then I
think it makes sense to complete the vacuum as fast as possible -- which
includes not trying to summarize it for brin indexes.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
