RE: Initial COPY of Logical Replication is too slow

Dear Sawada-san,

Thanks for updating the patch! Few 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 published in the
+ * first place. If not, we can return early without checking 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_parent, gpt_test_sch.tbl_sch) WITH (publish_via_partition_root = 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 = true);
```

It needs to be rebased due to 5984ea86.

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 = GPT.relid AND
a.attnum = 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 = C.relnamespace)
WHERE C.oid = 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 = C.relnamespace)
- WHERE C.oid = GPT.relid;
+ pg_class C JOIN pg_namespace N ON (N.oid = C.relnamespace),
+ LATERAL pg_get_publication_tables(ARRAY[P.pubname], C.oid) GPT;
```

Best regards,
Hayato Kuroda
FUJITSU LIMITED