Re: Initial COPY of Logical Replication is too slow

On Wed, Apr 1, 2026 at 11:12 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
>
> Hi Sawada-San
>
> Some review comments for v8-0001.
>
> ======
> Commit message
>
> 1.
> The existing a VARIADIC array form of pg_get_publication_tables() is
> preserved for backward compatibility. Tablesync workers use the new
> two-argument form when connected to a publisher running PostgreSQL 19
> or later.
>
> ~
>
> Typo? "The existing a VARIADIC"
>
> ======
> src/backend/catalog/pg_publication.c
>
> is_publishable_table:
>
> 2.
> + /*
> + * Sequences are publishable according to is_publishable_class() so
> + * explicitly exclude here.
> + */
> + if (relform->relkind != RELKIND_SEQUENCE &&
> + is_publishable_class(tableoid, relform))
> + {
> + ReleaseSysCache(tuple);
> + return true;
> + }
>
> It seemed strange to say that "sequences are publishable according to
> is_publishable_class() so explicitly exclude", but then you proceed to
> call is_publishable_class() anyway.
>
> Maybe using a variable, and a different comment could be a better way
> of expressing this?
>
> SUGGESTION
> bool ret;
> ...
> /* Sequences are not tables, so this function returns false. */
> if (relform->relkind == RELKIND_SEQUENCE)
> ret = false;
> else
> ret = is_publishable_class(tableoid, relform);
>
> ReleaseSysCache(tuple);
> return ret;
>
> ~~~
>
> is_table_publishable_in_publication:
>
> 3.
> + * A helper function for pg_get_publication_tables() to check whether the
> + * table of the given relid is published for the specified publication.
>
> /table of the given relid/table with the given relid/
>
> /is published for the/is published in the/
>
> ~~~
>
> pg_get_publication_tables:
>
> 4.
> + * If filter_by_relid is true, only the row for target_relid is returned;
> + * if target_relid does not exist or is not part of the publications, zero
> + * rows are returned. If filter_by_relid is false, rows for all tables
> + * within the specified publications are returned and target_relid is
> + * ignored.
>
> Should that say "only the row(s) for target_relid", e.g. possibly
> plural, because if same table is in multiple publications then there
> are be multiple result rows, right?
>
> ======
> src/include/catalog/pg_proc.dat
>
> 5.
> Missed my previous [1] review comment #4?
>
> First arg of pg_get_publication_tables_a should be plural 'pubnames',
> same as first arg of pg_get_publication_tables_b.
>
> ======
> src/test/regress/sql/publication.sql
>
> 6.
> +CREATE PUBLICATION pub_all_except_no_viaroot FOR ALL TABLES EXCEPT
> (TABLE tbl_parent, gpt_test_sch.tbl_sch) WITH
> (publish_via_partition_root = true);
>
> Why is this publication called '...no_viaroot' when
> publish_via_partition_root = true?
>
> ~~~
>
> 7.
> +-- test for the EXCLUDE clause
>
> Typo? /EXCLUDE clause/EXCEPT clause/
>

Thank you for the comments!

I've pushed the patch after incorporating these points.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com