Re: Pgoutput not capturing the generated columns

On Fri, Sep 20, 2024 at 2:26 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Fri, Sep 20, 2024 at 4:16 AM Peter Smith <smithpb2250@gmail.com> wrote:
> >
> > On Fri, Sep 20, 2024 at 3:26 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > On Thu, Sep 19, 2024 at 2:32 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > >
> > > >
> > > > Users can use a publication like "create publication pub1 for table
> > > > t1(c1, c2), t2;" where they want t1's generated column to be published
> > > > but not for t2. They can specify the generated column name in the
> > > > column list of t1 in that case even though the rest of the tables
> > > > won't publish generated columns.
> > >
> > > Agreed.
> > >
> > > I think that users can use the publish_generated_column option when
> > > they want to publish all generated columns, instead of specifying all
> > > the columns in the column list. It's another advantage of this option
> > > that it will also include the future generated columns.
> > >
> >
> > OK. Let me give some examples below to help understand this idea.
> >
> > Please correct me if these are incorrect.
> >
> > Examples, when publish_generated_columns=true:
> >
> > CREATE PUBLICATION pub1 FOR t1(a,b,gen2), t2 WITH
> > (publish_generated_columns=true)
> > t1 -> publishes a, b, gen2 (e.g. what column list says)
> > t2 -> publishes c, d + ALSO gen1, gen2
> >
> > CREATE PUBLICATION pub1 FOR t1, t2(gen1) WITH (publish_generated_columns=true)
> > t1 -> publishes a, b + ALSO gen1, gen2
> > t2 -> publishes gen1 (e.g. what column list says)
> >
>
> These two could be controversial because one could expect that if
> "publish_generated_columns=true" then publish generated columns
> irrespective of whether they are mentioned in column_list. I am of the
> opinion that column_list should take priority the results should be as
> mentioned by you but let us see if anyone thinks otherwise.
>
> >
> > ======
> >
> > The idea LGTM, although now the parameter name
> > ('publish_generated_columns') seems a bit misleading since sometimes
> > generated columns get published "irrespective of the option".
> >
> > So, I think the original parameter name 'include_generated_columns'
> > might be better here because IMO "include" seems more like "add them
> > if they are not already specified", which is exactly what this idea is
> > doing.
> >
>
> I still prefer 'publish_generated_columns' because it matches with
> other publication option names. One can also deduce from
> 'include_generated_columns' that add all the generated columns even
> when some of them are specified in column_list.
>

Fair point. Anyway, to avoid surprises it will be important for the
precedence rules to be documented clearly (probably with some
examples),

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Kind Regards,
Peter Smith.
Fujitsu Australia