Re: Pgoutput not capturing the generated columns

On Mon, Jun 3, 2024 at 9:52 PM Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com> wrote:
>
> >
> > The attached Patch contains the suggested changes.
> >
>
> Hi,
>
> Currently, COPY command does not work for generated columns and
> therefore, COPY of generated column is not supported during tablesync
> process. So, in patch v4-0001 we added a check to allow replication of
> the generated column only if 'copy_data = false'.
>
> I am attaching patches to resolve the above issues.
>
> v5-0001: not changed
> v5-0002: Support COPY of generated column
> v5-0003: Support COPY of generated column during tablesync process
>

Hi Shlok, I have a question about patch v5-0003.

According to the patch 0001 docs "If the subscriber-side column is
also a generated column then this option has no effect; the replicated
data will be ignored and the subscriber column will be filled as
normal with the subscriber-side computed or default data".

Doesn't this mean it will be a waste of effort/resources to COPY any
column value where the subscriber-side column is generated since we
know that any copied value will be ignored anyway?

But I don't recall seeing any comment or logic for this kind of copy
optimisation in the patch 0003. Is this already accounted for
somewhere and I missed it, or is my understanding wrong?

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Kind Regards,
Peter Smith.
Fujitsu Australia