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From: Masahiko Sawada <sawada.mshk@gmail.com>
Date: Tue, 31 Mar 2026 12:29:37 -0700
Message-ID: 
 <CAD21AoC1wHPESMoNvef+3_+G8assoi966Adm0AiYcz+YW9RAmQ@mail.gmail.com>
Subject: Re: Initial COPY of Logical Replication is too slow
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>,
 Amit Kapila <amit.kapila16@gmail.com>,
	Jan Wieck <jan@wi3ck.info>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
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On Tue, Mar 31, 2026 at 4:39=E2=80=AFAM Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> Dear Sawada-san,
>
> Thanks for updating the patch! Few comments.

Thank you for the comments!

>
> 01.
> ```
> +/*
> + * Similar to is_publishable_calss() but checks whether the given OID
> + * is a publishable "table" or not.
> + */
> +static bool
> +is_publishable_table(Oid tableoid)
> ```
>
> s/is_publishable_calss/is_publishable_class/.
>
> 02.
> ```
> +       ReleaseSysCache(tuple);
> +       return true;
> ```
>
> Is it correct? I expected to return false here.
>
> 03.
> ```
> +               /*
> +                * Preliminary check if the specified table can be publis=
hed in the
> +                * first place. If not, we can return early without check=
ing the given
> +                * publications and the table.
> +                */
> +               if (filter_by_relid && !is_publishable_table(target_relid=
))
> +                       SRF_RETURN_DONE(funcctx);
> ```
>
> I think we must switch to the old context.
>
> 04.
> ```
> +CREATE PUBLICATION pub_all_except FOR ALL TABLES EXCEPT TABLE (tbl_paren=
t, gpt_test_sch.tbl_sch) WITH (publish_via_partition_root =3D false);
> +CREATE PUBLICATION pub_all_except_no_viaroot FOR ALL TABLES EXCEPT TABLE=
 (tbl_parent, gpt_test_sch.tbl_sch) WITH (publish_via_partition_root =3D tr=
ue);
> ```
>
> It needs to be rebased due to 5984ea86.

Agreed with the all above points. I'll fix them in the next version patch.

>
> 05.
> ```
> CREATE VIEW pg_publication_tables AS
>     SELECT
>         P.pubname AS pubname,
>         N.nspname AS schemaname,
>         C.relname AS tablename,
>         ( SELECT array_agg(a.attname ORDER BY a.attnum)
>           FROM pg_attribute a
>           WHERE a.attrelid =3D GPT.relid AND
>                 a.attnum =3D ANY(GPT.attrs)
>         ) AS attnames,
>         pg_get_expr(GPT.qual, GPT.relid) AS rowfilter
>      FROM pg_publication P,
>           LATERAL pg_get_publication_tables(P.pubname) GPT,
>           pg_class C JOIN pg_namespace N ON (N.oid =3D C.relnamespace)
>      WHERE C.oid =3D GPT.relid;
> ```
>
> Can we use the new API of pg_get_publication_tables() here? Below change =
can pass
> tests on my env.
>
> ```
> -         LATERAL pg_get_publication_tables(P.pubname) GPT,
> -         pg_class C JOIN pg_namespace N ON (N.oid =3D C.relnamespace)
> -    WHERE C.oid =3D GPT.relid;
> +         pg_class C JOIN pg_namespace N ON (N.oid =3D C.relnamespace),
> +         LATERAL pg_get_publication_tables(ARRAY[P.pubname], C.oid) GPT;
> ```

I'm not sure the new API of pg_get_publication_tables() is better here
since this view is going to get the publication information of all
published tables, in which case the existing one might be faster.
Also, if a few tables among a huge number of tables (or whatever
relations) are published, checking all relations with the new API of
pg_get_publication_tables() would be quite slow.

Regards,

--=20
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com