Re: PATCH: Using BRIN indexes for sorted output

Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> writes:
> I forgot to mention one important issue in my list yesterday, and that's
> memory consumption.

TBH, this is all looking like vastly more complexity than benefit.
It's going to be impossible to produce a reliable cost estimate
given all the uncertainty, and I fear that will end in picking
BRIN-based sorting when it's not actually a good choice.

The examples you showed initially are cherry-picked to demonstrate
the best possible case, which I doubt has much to do with typical
real-world tables. It would be good to see what happens with
not-perfectly-sequential data before even deciding this is worth
spending more effort on. It also seems kind of unfair to decide
that the relevant comparison point is a seqscan rather than a
btree indexscan.

regards, tom lane