Re: Temporarily very slow planning time after a big delete

On Tue, May 21, 2019 at 11:15 AM Peter Geoghegan <[email protected]> wrote:

> On Tue, May 21, 2019 at 11:12 AM Walter Smith <[email protected]> wrote
> > I did a VACUUM overnight and got the following. The thing that stands
> out to me is that one index (index_unproc_notifications_on_notifiable_type)
> took 100x longer to scan than the others. That's not the index used in the
> slow query, though.
>
> What columns are indexed by
> index_unproc_notifications_on_notifiable_type, and what are their
> datatypes?
>

It occurs to me that is a somewhat unusual index -- it tracks unprocessed
notifications so it gets an insert and delete for every row, and is
normally almost empty.

Index "public.index_unproc_notifications_on_notifiable_type"
     Column      |          Type          |   Definition
-----------------+------------------------+-----------------
 notifiable_type | character varying(255) | notifiable_type
btree, for table "public.notifications", predicate (processed = false)

Thanks,
Walter