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Re: ALTER TABLE SET ACCESS METHOD on partitioned tables

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Peter Eisentraut <peter@eisentraut.org>, Soumyadeep Chakraborty <soumyadeep2007@gmail.com>, Zhihong Yu <zyu@yugabyte.com>, pgsql-hackers@postgresql.org, Ashwin Agrawal <ashwinstar@gmail.com>, vanjared@vmware.com
Date: 2024-03-08T02:02:00Z
Lists: pgsql-hackers

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On Mon, Mar 04, 2024 at 05:46:56PM +0900, Michael Paquier wrote:
> > Since InvalidOid is already taken, I guess you might need to introduce a
> > boolean flag, like set_relam, indicating that the statement has an
> > ACCESS METHOD clause.
> 
> Yes, I don't see an alternative.  The default needs a different field
> to be tracked down to the execution.

The data structure you used (defaultAccessMethod) allows this, which
is intended to be prohibited:

postgres=# ALTER TABLE a SET access method default, SET access method default;
ALTER TABLE

As you wrote it, you pass the "defaultAccessMethod" bool to
ATExecSetAccessMethodNoStorage(), which seems odd.  Why not just pass
the target amoid as newAccessMethod ?

When I fooled with this on my side, I called it "chgAccessMethod" to
follow "chgPersistence".  I think "is default" isn't the right data
structure.

Attached a relative patch with my version.

Also: I just realized that instead of adding a bool, we could test
(tab->rewrite & AT_REWRITE_ACCESS_METHOD) != 0

+-- Default and AM set in in clause are the same, relam should be set.

in in?

-- 
Justin

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add information about access method for partitioned relations in \dP+

  2. Fix dumps of partitioned tables with table AMs

  3. Don't use the pg_am system catalog in new test

  4. ALTER TABLE: rework determination of access method ID

  5. Allow specifying an access method for partitioned tables

  6. Review wording on tablespaces w.r.t. partitioned tables

  7. Add support for DEFAULT in ALTER TABLE .. SET ACCESS METHOD

  8. Update comment of AlterTableCmd->name in parsenodes.h