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Re: Pgoutput not capturing the generated columns

Shlok Kyal <shlok.kyal.oss@gmail.com>

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From: Shlok Kyal <shlok.kyal.oss@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: Shubham Khanna <khannashubham1197@gmail.com>, Rajendra Kumar Dangwal <dangwalrajendra888@gmail.com>, pgsql-hackers@lists.postgresql.org, euler@eulerto.com
Date: 2024-06-15T10:46:57Z
Lists: pgsql-hackers 
On Wed, 5 Jun 2024 at 05:49, Peter Smith <smithpb2250@gmail.com> wrote:
>
> On Mon, Jun 3, 2024 at 9:52 PM Shlok Kyal <shlok.kyal.oss@gmail.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?
Your understanding is correct.
With v7-0002, if a subscriber-side column is generated, then we do not
include that column in the column list during COPY. This will address
the above issue.

Patch 7-0002 contains all the changes. Please refer [1]
[1]: https://www.postgresql.org/message-id/CANhcyEUz0FcyR3T76b%2BNhtmvWO7o96O_oEwsLZNZksEoPmVzXw%40mail.gmail.com

Thanks and Regards,
Shlok Kyal

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Doc: Generated column replication.

  2. Rename pubgencols_type to pubgencols in pg_publication.

  3. Doc: Fix column name in pg_publication catalog.

  4. Fix buildfarm failure introduced by commit e65dbc9927.

  5. Change publication's publish_generated_columns option type to enum.

  6. Fix \dRp+ output when describing publications with a lower server version.

  7. Replicate generated columns when 'publish_generated_columns' is set.

  8. Doc: Update the behavior of generated columns in Logical Replication.

  9. Replicate generated columns when specified in the column list.

  10. Doc: Generated columns are skipped for logical replication.