On Fri, 10 Jan 2020 at 20:54, Mahendra Singh Thalor <
mahi6run@gmail.com> wrote:
>
> 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.
I don't think the change is a good idea.
- bool skip_index = (get_indstats(lps->lvshared, i) == NULL ||
- skip_parallel_vacuum_index(Irel[i], lps->lvshared));
+ bool can_parallel = (get_indstats(lps->lvshared, i) == NULL ||
+ skip_parallel_vacuum_index(Irel[i],
+ lps->lvshared));
The above condition is true when the index can *not* do parallel index vacuum. How about changing it to skipped_index and change the comment to something like “We are interested in only index skipped parallel vacuum”?
>
> >
> > 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 tables in 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.
+1
--