Re: Column Filtering in Logical Replication

On 2021-Dec-17, Rahila Syed wrote:

> > This means that we need to support changing the column list of a
> > table in a publication.  I'm looking at implementing some form of
> > ALTER PUBLICATION for that.
>
> I think right now the patch contains support only for ALTER
> PUBLICATION..  ADD TABLE with column filters.  In order to achieve
> changing the column lists of a published table, I think we can extend
> the ALTER TABLE ..SET TABLE syntax to support specification of column
> list.

Yeah, that's what I was thinking too.

> > So this whole thing can be reduced to just this:
> 
> > if (att_map != NULL && !bms_is_member(att->attnum, att_map))
> >        continue;        /* that is, don't send this attribute */
> 
> I agree the condition can be shortened now. The long if condition was
> included because initially the feature allowed specifying filters
> without replica identity columns(sent those columns internally without
> user having to specify).

Ah, true, I had forgotten that.  Thanks.

> >  900 +        * the table is partitioned.  Run a recursive query to iterate through all
> >  901 +        * the parents of the partition and retreive the record for the parent
> >  902 +        * that exists in pg_publication_rel.
> >  903 +        */
> 
> The above comment in fetch_remote_table_info() can be changed as the
> recursive query is no longer used.

Oh, of course.

I'll finish some loose ends and submit a v10, but it's still not final.

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