Re: Hash Indexes

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Oct 18, 2016 at 5:37 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> I have implemented this idea and it works for MVCC scans.  However, I
>> think this might not work for non-MVCC scans.  Consider a case where
>> in Process-1, hash scan has returned one row and before it could check
>> it's validity in heap, vacuum marks that tuple as dead and removed the
>> entry from heap and some new tuple has been placed at that offset in
>> heap.

> Oops, that's bad.

Do we care?  Under what circumstances would a hash index be used for a
non-MVCC scan?
        regards, tom lane