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.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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