Good afternoon!

I am finding it difficult to understand how to maintain my BRIN index from
the docs.  Specifically, this is the documentation on the
function brin_summarize_range which isn't clear to me:

brin_summarize_range(index regclass, blockNumber bigint) integer

   - summarize the page range covering the given block, if not already
   summarized

There is no information on how a user is to actually find blockNumber,
especially what blockNumber she might be interested in (like the end of the
table).  On my table, my BRIN index is all of a sudden all out of whack and
I'm trying to figure out why.  The planner doesn't choose it.  Even if I
force a BRIN scan, it estimates way wrong, and performs terribly.  I do not
have autosummarize on.  I am curious if vacuum somehow invalidated
everything?

When I ran brin_summarize_new_values, it immediately returned 0.  This
table has 292 million rows, and a straightforward insert-only pattern, but
we also prune data older than 1 year old. The BRIN index is on insert
time.  It was working great up until just a bit ago.

Any direction on using these brin functions would be very appreciated.

Thanks,
Jeremy

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