Re: [HACKERS] [PATCH] Generic type subscripting - Mailing list pgsql-hackers

From Alexander Korotkov
Subject Re: [HACKERS] [PATCH] Generic type subscripting
Date
Msg-id CAPpHfdsw-mz-TWmMZNVDoquB1ETYmiDmtKPt67MJcTCn2cks0w@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] [PATCH] Generic type subscripting  (Dmitry Dolgov <9erthalion6@gmail.com>)
Responses Re: [HACKERS] [PATCH] Generic type subscripting
List pgsql-hackers
On Wed, Dec 2, 2020 at 10:18 PM Dmitry Dolgov <9erthalion6@gmail.com> wrote:
> > On Wed, Dec 02, 2020 at 11:52:54AM -0500, Tom Lane wrote:
> > Dmitry Dolgov <9erthalion6@gmail.com> writes:
> > >> On Mon, Nov 30, 2020 at 02:26:19PM +0100, Dmitry Dolgov wrote:
> > >>> On Mon, Nov 30, 2020 at 04:12:29PM +0300, Alexander Korotkov wrote:
> > >>> The idea of an opaque field in SubscriptingRef structure is more
> > >>> attractive to me.  Could you please implement it?
> >
> > >> Sure, doesn't seem to be that much work.
> >
> > I just happened to notice this bit.  This idea is a complete nonstarter.
> > You cannot have an "opaque" field in a parsetree node, because then the
> > backend/nodes code has no idea what to do with it for
> > copy/compare/outfuncs/readfuncs.  The patch seems to be of the opinion
> > that "do nothing" is adequate, which it completely isn't.
> >
> > Perhaps this is a good juncture at which to remind people that parse
> > tree nodes are read-only so far as the executor is concerned, so
> > storing something there only at execution time won't work either.
>
> Oh, right, stupid of me. Then I'll just stick with the original
> Alexanders suggestion.

Stupid me too :)

I didn't get we can't add opaque field to SubscriptingRefState without
adding it to SubscriptingRef, which has to support
copy/compare/outfuncs/readfuncs

------
Regards,
Alexander Korotkov



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