Re: [HACKERS] Block level parallel vacuum

On Fri, 10 Jan 2020 at 15:51, Sergei Kornilov <sk@zsrv.org> wrote:
>
> Hi
> Thank you for update! I looked again
>
> (vacuum_indexes_leader)
> +               /* Skip the indexes that can be processed by parallel workers */
> +               if (!skip_index)
> +                       continue;
>
> Does the variable name skip_index not confuse here? Maybe rename to something like can_parallel?

I also agree with your point.

>
> Another question about behavior on temporary tables. Use case: the user commands just "vacuum;" to vacuum entire
database(and has enough maintenance workers). Vacuum starts fine in parallel, but on first temporary table we hit:
 
>
> +       if (RelationUsesLocalBuffers(onerel) && params->nworkers >= 0)
> +       {
> +               ereport(WARNING,
> +                               (errmsg("disabling parallel option of vacuum on \"%s\" --- cannot vacuum temporary
tablesin parallel",
 
> +                                               RelationGetRelationName(onerel))));
> +               params->nworkers = -1;
> +       }
>
> And therefore we turn off the parallel vacuum for the remaining tables... Can we improve this case?

Good point.
Yes, we should improve this. I tried to fix this.  Attaching a delta
patch that is fixing both the comments.

-- 
Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com