Re: REPACK (CONCURRENTLY) rewrites tables marked with user_catalog_table

Hello,

On 2026-Sep-04, Masahiko Sawada wrote:

> I reviewed the patch. It's simple and I agree to add a check for user
> catalog tables. I've slightly rephrased the comment in
> check_concurrent_repack_requirements() to clarify the reason why
> REPACK (CONCURRENTLY) doesn't support user catalog tables while it
> does for normal tables even though it's a MVCC-unsafe operation. Also
> updated the commit message as well. Please review it.

Thanks, I gave this a look and I think it's okay. I'm not sure about
the exact wording of the error message though,

> + ereport(ERROR,
> + errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> + errmsg("cannot execute %s on relation \"%s\"",
> + "REPACK (CONCURRENTLY)", RelationGetRelationName(rel)),
> + errhint("%s is not supported for tables used as catalog tables.",
> + "REPACK (CONCURRENTLY)"));

ERROR: cannot execute REPACK (CONCURRENTLY) on relation "foobar"
HINT: REPACK (CONCURRENTLY) is not supported for tables used as catalog tables.

I think the HINT should really be DETAIL, and I'm not sure we need to
mention the command again there. On the other hand, I'm not really
happy with the term "tables used as catalog tables". In the
documentation we use the term "user provided catalog tables" or simply
"user catalog tables" (see <sect2 id="logicaldecoding-capabilities">).
So how about something like this?

ERROR: cannot execute REPACK (CONCURRENTLY) on relation "foobar"
DETAIL: This operation is not supported for user catalog tables.

Would you push this patch, or do you want me to?

Thanks!

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/