Re: Add MAIN_RELATION_CLEANUP and SECONDARY_RELATION_CLEANUP options to VACUUM

On 1/21/20, 1:39 PM, "Vik Fearing" <vik(dot)fearing(at)2ndquadrant(dot)com> wrote:
> On 21/01/2020 22:21, Bossart, Nathan wrote:
>> I've attached a patch for a couple of new options for VACUUM:
>> MAIN_RELATION_CLEANUP and SECONDARY_RELATION_CLEANUP. The motive
>> behind these options is to allow table owners to easily vacuum only
>> the TOAST table or only the main relation. This is especially useful
>> for TOAST tables since roles do not have access to the pg_toast schema
>> by default and some users may find it difficult to discover the name
>> of a relation's TOAST table.
>
>
> Could you explain why one would want to do this? Autovacuum will
> already deal with the tables separately as needed, but I don't see when
> a manual vacuum would want to make this distinction.

The main use case I'm targeting is when the level of bloat or
transaction ages of a relation and its TOAST table have significantly
diverged. In these scenarios, it could be beneficial to be able to
vacuum just one or the other, especially if the tables are large.

Nathan