Re: Pgoutput not capturing the generated columns

On Wed, Oct 9, 2024 at 9:08 AM vignesh C <vignesh21@gmail.com> wrote:
>
> On Tue, 8 Oct 2024 at 11:37, Shubham Khanna <khannashubham1197@gmail.com> wrote:
> >
> > On Fri, Oct 4, 2024 at 9:36 AM Peter Smith <smithpb2250@gmail.com> wrote:
> > >
> > > Hi Shubham, here are my review comments for v36-0001.
> > >
> > > ======
> > > 1. General  - merge patches
> > >
> > > It is long past due when patches 0001 and 0002 should've been merged.
> > > AFAIK the split was only because historically these parts had
> > > different authors. But, keeping them separated is not helpful anymore.
> > >
> > > ======
> > > src/backend/catalog/pg_publication.c
> > >
> > > 2.
> > >  Bitmapset *
> > > -pub_collist_validate(Relation targetrel, List *columns)
> > > +pub_collist_validate(Relation targetrel, List *columns, bool pubgencols)
> > >
> > > Since you removed the WARNING, this parameter 'pubgencols' is unused
> > > so it should also be removed.
> > >
> > > ======
> > > src/backend/replication/pgoutput/pgoutput.c
> > >
> > > 3.
> > >   /*
> > > - * If the publication is FOR ALL TABLES then it is treated the same as
> > > - * if there are no column lists (even if other publications have a
> > > - * list).
> > > + * To handle cases where the publish_generated_columns option isn't
> > > + * specified for all tables in a publication, we must create a column
> > > + * list that excludes generated columns. So, the publisher will not
> > > + * replicate the generated columns.
> > >   */
> > > - if (!pub->alltables)
> > > + if (!(pub->alltables && pub->pubgencols))
> > >
> > > I still found that comment hard to understand. Does this mean to say
> > > something like:
> > >
> > > ------
> > > Process potential column lists for the following cases:
> > >
> > > a. Any publication that is not FOR ALL TABLES.
> > >
> > > b. When the publication is FOR ALL TABLES and
> > > 'publish_generated_columns' is false.
> > > A FOR ALL TABLES publication doesn't have user-defined column lists,
> > > so all columns will be replicated by default. However, if
> > > 'publish_generated_columns' is set to false, column lists must still
> > > be created to exclude any generated columns from being published
> > > ------
> > >
> > > ======
> > > src/test/regress/sql/publication.sql
> > >
> > > 4.
> > > +SET client_min_messages = 'WARNING';
> > > +CREATE TABLE gencols (a int, gen1 int GENERATED ALWAYS AS (a * 2) STORED);
> > >
> > > AFAIK you don't need to keep changing 'client_min_messages',
> > > particularly now that you've removed the WARNING message that was
> > > previously emitted.
> > >
> > > ~
> > >
> > > 5.
> > > nit - minor comment changes.
> > >
> > > ======
> > > Please refer to the attachment which implements any nits from above.
> > >
> >
> > I have fixed all the given comments. Also, I have created a new 0003
> > patch for the TAP-Tests related to the '011_generated.pl' file. I am
> > planning to merge 0001 and 0003 patches once they will get fixed.
> > The attached patches contain the required changes.
>
> Few comments:
> 1) Since we are no longer throwing an error for generated columns, the
> function header comments also need to be updated accordingly " Checks
> for and raises an ERROR for any; unknown columns, system columns,
> duplicate columns or generated columns."
> -               if (TupleDescAttr(tupdesc, attnum - 1)->attgenerated)
> -                       ereport(ERROR,
> -
> errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
> -                                       errmsg("cannot use generated
> column \"%s\" in publication column list",
> -                                                  colname));
> -
>
> 2) Tab completion missing for "PUBLISH_GENERATED_COLUMNS" option in
> ALTER PUBLICATION ... SET (
> postgres=# alter publication pub2 set (PUBLISH
> PUBLISH                     PUBLISH_VIA_PARTITION_ROOT
>
> 3) I was able to compile without this include, may be this is not required:
> --- a/src/backend/replication/logical/tablesync.c
> +++ b/src/backend/replication/logical/tablesync.c
> @@ -118,6 +118,7 @@
>  #include "utils/builtins.h"
>  #include "utils/lsyscache.h"
>  #include "utils/memutils.h"
> +#include "utils/rel.h"
>
> 4) You can include "\dRp+ pubname" after each of the create/alter
> publication to verify the columns that will be published:
> +-- Test the 'publish_generated_columns' parameter enabled or disabled for
> +-- different scenarios with/without generated columns in column lists.
> +CREATE TABLE gencols (a int, gen1 int GENERATED ALWAYS AS (a * 2) STORED);
> +
> +-- Generated columns in column list, when 'publish_generated_columns'=false
> +CREATE PUBLICATION pub1 FOR table gencols(a, gen1) WITH
> (publish_generated_columns=false);
>
> +-- Generated columns in column list, when 'publish_generated_columns'=true
> +CREATE PUBLICATION pub2 FOR table gencols(a, gen1) WITH
> (publish_generated_columns=true);
> +
> +-- Generated columns in column list, then set
> 'publication_generate_columns'=false
> +ALTER PUBLICATION pub2 SET (publish_generated_columns = false);
> +
> +-- Remove generate columns from column list, when
> 'publish_generated_columns'=false
> +ALTER PUBLICATION pub2 SET TABLE gencols(a);
> +
> +-- Add generated columns in column list, when 'publish_generated_columns'=false
> +ALTER PUBLICATION pub2 SET TABLE gencols(a, gen1);
>

I have fixed all the given comments. The attached patches contain the
required changes.

Thanks and Regards,
Shubham Khanna.