Re: pg_dump/pg_restore fail for TAR_DUMP and CUSTOM_DUMP from v94/v95/v96 to v11/master.

Hi,

The Commit 5955d934194c3888f30318209ade71b53d29777f has changed the logic
to avoid dumping creation and comment commands for the public schema.
From v11 onwards, we are using the DUMP_COMPONENT_ infrastructure in
selectDumpableNamespace() to skip the public schema creation.

As reported by Prabhat, if we try to restore the custom/tar dump taken from
v10 and earlier versions, we get the reported error for public schema.
The reason for this error is, when we take custom/tar dump from v10 and
earlier version, it has "CREATE SCHEMA public;" statement and v11 failed to
bypass that as per the current logic.

The plain format does not produces the error in this case, because in all
versions, pg_dump in plain format does not generate that "CREATE SCHEMA
public". In v10 and earlier, we filter out that public schema creation in
_printTocEntry() while pg_dump.

In custom/tar format, pg_dump in V10 and earlier versions generate the
schema creation statement for public schema but again while pg_restore in
same or back branches, it get skipped through same _printTocEntry()
function.

I think we can write a logic in -
1) BulidArchiveDependencies() to avoid dumping creation and comment
commands for the public schema since we do not have DUMP_COMPONENT_
infrastructure in all supported back-branches.
or
2) dumpNamespace() to not include public schema creation.

Thoughts?

Regards,
Suraj