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Re: ALTER TABLE SET ACCESS METHOD on partitioned tables

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Soumyadeep Chakraborty <soumyadeep2007@gmail.com>, Zhihong Yu <zyu@yugabyte.com>, pgsql-hackers@postgresql.org, Ashwin Agrawal <ashwinstar@gmail.com>, vanjared@vmware.com
Date: 2023-03-28T05:56:28Z
Lists: pgsql-hackers 
On Mon, Mar 27, 2023 at 11:34:35PM -0500, Justin Pryzby wrote:
> I realized that one difference with tablespaces is that, as written,
> partitioned tables will *always* have an AM specified,  and partitions
> will never use default_table_access_method.  Is that what's intended ?
>
> Or do we need logic similar tablespaces, such that the relam of a
> partitioned table is set only if it differs from default_table_am ?

Hmm.  This is a good point.  It is true that the patch feels
incomplete on this side.  I don't see why we could not be flexible,
and allow a value of 0 in a partitioned table's relam to mean that we
would pick up the database default in this case when a partition is
is created on it.  This would have the advantage to be consistent with
older versions where we fallback on the default.  We cannot be
completely consistent with the reltablespace of the leaf partitions
unfortunately, as relam should always be set if a relation has
storage.  And allowing a value of 0 means that there are likely other
tricky cases with dumps?

Another thing: would it make sense to allow an empty string in
default_table_access_method so as we'd always fallback to a database
default?
--
Michael

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