Re: ALTER TABLE SET ACCESS METHOD on partitioned tables

From: Justin Pryzby <pryzby(at)telsasoft(dot)com>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Soumyadeep Chakraborty <soumyadeep2007(at)gmail(dot)com>, Zhihong Yu <zyu(at)yugabyte(dot)com>, pgsql-hackers(at)postgresql(dot)org, Ashwin Agrawal <ashwinstar(at)gmail(dot)com>, vanjared(at)vmware(dot)com
Subject: Re: ALTER TABLE SET ACCESS METHOD on partitioned tables
Date: 2023-03-30 05:07:58
Message-ID: ZCUZLiCeXq4Im7OG@telsasoft.com
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On Mon, Mar 27, 2023 at 11:34:36PM -0500, Justin Pryzby wrote:
> On Tue, Mar 28, 2023 at 09:13:10AM +0900, Michael Paquier wrote:
> > On Mon, Mar 20, 2023 at 09:30:50AM +0900, Michael Paquier wrote:
> > > Did you check dump and restore flows with partition
> > > trees and --no-table-access-method? Perhaps there should be
> > > some regression tests with partitioned tables?
> >
> > I was looking at the patch, and as I suspected the dumps generated
> > are forgetting to apply the AM to the partitioned tables.
>
> The patch said:
>
> + else if (RELKIND_HAS_TABLE_AM(relkind) || relkind == RELKIND_PARTITIONED_TABLE)
>
> pg_dump was missing a similar change that's conditional on
> RELKIND_HAS_TABLE_AM(). It looks like those are the only two places
> that need be be specially handled.
>
> I dug up my latest patch from 2021 and incorporated the changes from the
> 0001 patch here, and added a test case.
>
> 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 ?

Actually .. I think it'd be a mistake if the relam needed to be
interpretted differently for partitioned tables than other relkinds.

I updated the patch to allow intermediate partitioned tables to inherit
relam from their parent.

Michael wrote:
> .. and there are quite more points to consider.

What more points ? There's nothing that's been raised here. In fact,
your message last week is the first comment since last June ..

--
Justin

Attachment Content-Type Size
0001-Allow-specifying-access-method-of-partitioned-tables.patch text/x-diff 19.4 KB

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