Re: [HACKERS] [Proposal] Make the optimiser aware of partitions ordering

On Wed, Sep 27, 2017 at 2:59 AM, Julien Rouhaud <rjuju123@gmail.com> wrote:
> On Tue, Sep 26, 2017 at 2:56 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Sat, Sep 23, 2017 at 6:29 AM, Julien Rouhaud <rjuju123@gmail.com> wrote:
>>> That's true, but numCols, sortColdIdx etc are also used to display the
>>> sort key in an explain.  If an append can return sorted data, it
>>> should also display the sort information, so I think these fields are
>>> still required in an Append node.
>>
>> I don't think so.  An index scan doesn't output that information, nor
>> does a nested loop which inherits a sort order from its outer path.  I
>> think the rule is that a plan node which takes steps to get the data
>> into a certain order might want to output something about that, but a
>> plan node which somehow gets that ordering without taking any explicit
>> action doesn't print anything.
>
> Oh, ok that indeed makes sense.  As I said I'll remove all the useless
> noise and send an updated patch.  Thanks again.

Waiting for a patch update for two months now, so marked as returned
with feedback.
-- 
Michael