Re: Pgoutput not capturing the generated columns

On Mon, Sep 23, 2024 at 4:10 AM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
>
> On Fri, Sep 20, 2024 at 2:26 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Fri, Sep 20, 2024 at 4:16 AM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
> > >
> > > On Fri, Sep 20, 2024 at 3:26 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > > >
> > > > On Thu, Sep 19, 2024 at 2:32 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)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),
>

Yeah, one or two examples would be good, but we can have a separate
doc patch that has clearly mentioned all the rules.

--
With Regards,
Amit Kapila.