Re: Initial COPY of Logical Replication is too slow

On Wed, Apr 1, 2026 at 11:06 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Tue, Mar 31, 2026 at 10:04 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Tue, Mar 31, 2026 at 10:58 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > >
> > > On Tue, Mar 31, 2026 at 2:36 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > >
> > > > On Wed, Mar 25, 2026 at 2:19 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
> > > > >
> > > > > Hi Swada-San. Here are some minor review comments for v4-0001/2 combined.
> > > > >
> > > > > ======
> > > > > src/backend/catalog/pg_publication.c
> > > > >
> > > > > is_table_publishable_in_publication:
> > > > >
> > > > > 1.
> > > > > This function logic has a format like
> > > > >
> > > > > if (cond)
> > > > > {
> > > > > ...
> > > > > return;
> > > > > }
> > > > >
> > > > > if (cond2)
> > > > > {
> > > > > ...
> > > > > return;
> > > > > }
> > > > >
> > > > > etc.
> > > > >
> > > > > There are many return points, and most of those "if" blocks cannot
> > > > > fall through (they return).
> > > > >
> > > > > I found it slightly difficult to read the code because I kept having
> > > > > to think, "OK, if we reached here, it means pubviaroot must be false,"
> > > > > or "OK, if we reached this far, then puballtables must be false, and
> > > > > pubviaroot must be false," etc.
> > > > >
> > > >
> > > > I can't say exactly why, but I find it difficult to read this
> > > > function. So, I share your concerns about the code of this function.
> > > > Because of its complexity it is difficult to ascertain that the
> > > > functionality is correct or we missed something. Also, considering it
> > > > is correct today, in its current form, it may become difficult to
> > > > enhance it in future.
> > >
> > > Okay, I'll refactor that function.
> > >
> > > >
> > > > One more comment on latest patch:
> > > > *
> > > > +static Datum
> > > > +pg_get_publication_tables(FunctionCallInfo fcinfo, ArrayType *pubnames,
> > > > + Oid target_relid, bool filter_by_relid,
> > > >
> > > > Why do we need filter_by_relid as a separate parameter? Isn't the
> > > > valid value of target_relid the same? If so, can't we use target_relid
> > > > for the required checks?
> > >
> > > If we don't have filter_by_relid, we would end up not filtering
> > > anything if users pass 0 (InvalidOid) as the target_relid to the new
> > > pg_get_publication_tables(). This is the same as the behavior of the
> > > existing pg_get_publication_tables(),
> > >
> >
> > Isn't that what we want when a user passes InvalidOid? What is the
> > expected behavior in that case?
> >
>
> While it could be contrivarsial what we expect when "users wants to
> filter the result by InvalidOid", I think the new
> pg_get_publication_tables() should not return anything in this case
> rather than return all table information. I think this behavior is
> consistent with the case where users pass non-table OID to the
> function. I don't want to make passing InvalidOid a special case in
> the new function.
>

Fair enough. I am fine with this definition.

--
With Regards,
Amit Kapila.