Re: ToDo: KNN Search should to support DISTINCT clasuse?

Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Oct 22, 2012 at 11:57 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Don't hold your breath.  There are two ways the system could implement
>> the DISTINCT clause: either sort and uniq, or hashaggregate.
>> hashaggregate will destroy any input ordering, so there's no value in
>> using the index as input.

> Isn't that an implementation limitation though, rather than a
> fundamental limitation?

Perhaps, but it's not a simple one to surmount, and I'm dubious about
putting the amount of work that'd be required into such a corner case.
        regards, tom lane