Re: [HACKERS] Grouping Sets: Fix unrecognized node type bug

Hello, this looks to be a kind of thinko. The attached patch
fixes it.

===
According to the comment of transformGroupingSet, it assumes that
the given GROUPING SETS node is already flatted out and
flatten_grouping_sets() does that. The details of the
transformation is described in the comment for the function.

The problmen is what does the function for nested grouping sets.

> Node *n2 = flatten_grouping_sets(lfirst(l2), false, NULL);
> result_set = lappend(result_set, n2);

This does not flattens the list as required. n2 should be
concatenated if it is a list. The attached small patch fixes it
and the problematic query returns sane (perhaps) result.

# Though I don't know the exact definition of the syntax..

=# select sum(c) from gstest2 group by grouping sets ((), grouping sets ((), grouping sets (())));
sum
-----
12
12
12
(3 rows)

=# select sum(c) from gstest2 group by grouping sets ((a), grouping sets ((b), grouping sets ((c))));
sum
-----
10
2
6
6
8
4
(6 rows)

regards,

At Fri, 17 Jul 2015 11:37:26 +0530, Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote in <CAM2+6=XPRgumbqWTsczbECC3xjv4zH1ryQ3fwds5uajON1iq2A(at)mail(dot)gmail(dot)com>
> > Jeevan> It looks like we do support nested GROUPING SETS, I mean Sets
> > Jeevan> withing Sets, not other types. However this nesting is broken.
> >
> > Good catch, but I'm not yet sure your fix is correct; I'll need to look
> > into that.
> >
>
> Sure. Thanks.
>
> However I wonder why we are supporting GROUPING SETS inside GROUPING SETS.
> On Oracle, it is throwing an error.
> We are not trying to be Oracle compatible, but just curious to know.
>
> I have tried restricting it in attached patch.
>
> But it may require few comment adjustment.

--
Kyotaro Horiguchi
NTT Open Source Software Center