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

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От Julien Rouhaud
Тема Re: [HACKERS] [Proposal] Make the optimiser aware of partitions ordering
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Msg-id CAOBaU_atLPyCqgiNNxczAvGffWP8f7E-2piWFZriRwJPt-nwgg@mail.gmail.com
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Ответ на Re: [HACKERS] [Proposal] Make the optimiser aware of partitions ordering  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: [HACKERS] [Proposal] Make the optimiser aware of partitions ordering  (Michael Paquier <michael.paquier@gmail.com>)
Список pgsql-hackers
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.


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