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

On Tue, Sep 26, 2017 at 2:56 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Sat, Sep 23, 2017 at 6:29 AM, Julien Rouhaud <rjuju123(at)gmail(dot)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.