On Tue, Apr 9, 2024 at 11:37 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Alexander Korotkov <aekorotkov@gmail.com> writes:
> > On Tue, Apr 9, 2024 at 5:12 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> * OrClauseGroupKey is not a Node type, so why does it have
> >> a NodeTag? I wonder what value will appear in that field,
> >> and what will happen if the struct is passed to any code
> >> that expects real Nodes.
>
> > I used that to put both not-subject-of-transform nodes together with
> > hash entries into the same list. This is used to save the order of
> > clauses. I think this is an important property, and I have already
> > expressed it in [1].
>
> What exactly is the point of having a NodeTag in the struct though?
> If you don't need it to be a valid Node, that seems pointless and
> confusing. We certainly have plenty of other lists that contain
> plain structs without tags, so I don't buy that the List
> infrastructure is making you do that.
This code mixes Expr's and hash entries in the single list. The point
of having a NodeTag in the struct is the ability to distinguish them
later.
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Regards,
Alexander Korotkov