2012/10/22 Tom Lane <tgl@sss.pgh.pa.us>:
> 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.
I don't think so this use case is too special - but workaround working well
Regards
Pavel
>
> regards, tom lane
