Re: Prefetch

Matt Olson <molson@oceanconsulting.com> writes:
> Other databases like Oracle and DB2 implement some sort of row prefetch.  Has
> there been serious consideration of implementing something like a prefetch
> subsystem?

No.

> Does anyone have any opinions as to why this would be a bad idea for
> postgres?

We know even less than the OS does about disk layout, and not a lot more
than it about what our next request will be.  (If we're doing a seqscan,
then of course that's not true, but I would expect the OS to be able to
figure that one out and do readahead.)

You haven't shown us your problem queries, but I think that conventional
query tuning would be a more appropriate answer.  In particular I wonder
whether you shouldn't be looking at ways to calculate multiple
aggregates in parallel.

            regards, tom lane