Jeremy Finzel <finzelj(at)gmail(dot)com> writes:
> I have a very large table with 4 billion rows and a BRIN index on timestamp
> spanning from 2013 to present. I am running this simple query:
> SELECT MIN(created_at) FROM table;
> It is choosing a parallel seq scan as opposed to a BRIN bitmap scan.
> I can provide more info. But first - am I missing something obvious?
Yes: BRIN indexes don't provide any ordering information. A btree
index on created_at could be used to optimize this query, but without
one of those, seqscanning the whole table is the only possibility.
regards, tom lane