From: "Etsuro Fujita" <fujita.etsuro@lab.ntt.co.jp>
To: "'Shigeru Hanada'" <shigeru.hanada@gmail.com>
Cc: "'PostgreSQL-development'" <pgsql-hackers@postgresql.org>
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Subject: Re: inherit support for foreign tables
Date: Tue, 18 Feb 2014 19:24:50 +0900
Message-ID: <000901cf2c93$a7d67c60$f7837520$@etsuro@lab.ntt.co.jp>
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> From: Shigeru Hanada [mailto:shigeru.hanada@gmail.com]

> 2014-02-10 21:00 GMT+09:00 Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>:
> > (2014/02/07 21:31), Etsuro Fujita wrote:
> >> So, I've modified the patch so
> >> that we continue to disallow SET STORAGE on a foreign table *in the
> >> same manner as before*, but, as your patch does, allow it on an
> >> inheritance hierarchy that contains foreign tables, with the
> >> semantics that we quietly ignore the foreign tables and apply the
> >> operation to the plain tables, by modifying the ALTER TABLE simple
> recursion mechanism.
> >> Attached is the updated version of the patch.
>=20
> I'm not sure that allowing ALTER TABLE against parent table affects
> descendants even some of them are foreign table.  I think the rule should
> be simple enough to understand for users, of course it should be also
> consistent and have backward compatibility.

Yeah, the understandability is important.  But I think the flexibility is a=
lso important.  In other words, I think it is a bit too inflexible that we =
disallow e.g., SET STORAGE to be set on an inheritance tree that contains f=
oreign table(s) because we disallow SET STORAGE to be set on foreign tables=
 directly.

> If foreign table can be modified through inheritance tree, this kind of
> change can be done.
>=20
> 1) create foreign table as a child of a ordinary table
> 2) run ALTER TABLE parent, the foreign table is also changed
> 3) remove foreign table from the inheritance tree by ALTER TABLE child NO
> INHERIT parent
> 4) here we can't do same thing as 2), because it is not a child anymore.
>=20
> So IMO we should determine which ALTER TABLE features are allowed to fore=
ign
> tables, and allow them regardless of the recursivity.

What I think should be newly allowed to be set on foreign tables is

* ADD table_constraint
* DROP CONSTRAINT
* [NO] INHERIT parent_table

Thanks,

Best regards,
Etsuro Fujita


--=20
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