Re: Initial COPY of Logical Replication is too slow

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>
Cc: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Jan Wieck <jan(at)wi3ck(dot)info>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Initial COPY of Logical Replication is too slow
Date: 2026-03-27 03:51:38
Message-ID: CAA4eK1LR4GaoqD_pt-KZrroCTaQZ3HCT3BiU1qGTRQLWpNRHmg@mail.gmail.com
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On Fri, Mar 27, 2026 at 8:46 AM Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
> Dear Sawada-san,
>
> > When passing a non-existent publication name, the current behavior
> > raises an error while the new behavior does nothing (i.e., the
> > difference is calling GetPublicationByName() with missing_ok = true or
> > false).
>
> To confirm; It's because in PG18-, p.pubname was chosen from the pg_publication
> in the publisher, but this patch the name list is taken from the subscriber, right?
> If some publications are dropped on the publisher, the ERROR could be raised.
>
> For the backward compatibility I suggest switching the policy based on the API
> version. E.g.,
>
> ```
> static Datum
> pg_get_publication_tables(FunctionCallInfo fcinfo, ArrayType *pubnames,
> - Oid target_relid)
> + Oid target_relid, bool missing_ok)
> ...
> @@ -1631,7 +1631,7 @@ Datum
> pg_get_publication_tables_a(PG_FUNCTION_ARGS)
> {
> /* Get the information of the tables in the given publications */
> - return pg_get_publication_tables(fcinfo, PG_GETARG_ARRAYTYPE_P(0), InvalidOid);
> + return pg_get_publication_tables(fcinfo, PG_GETARG_ARRAYTYPE_P(0), InvalidOid, false);
> ```
>

Sounds like a good idea for backward compatibility.

--
With Regards,
Amit Kapila.

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