Re: Minmax indexes

On Thu, Jul 10, 2014 at 2:30 PM, Jaime Casanova <jaime(at)2ndquadrant(dot)com>
wrote:

> On Thu, Jul 10, 2014 at 3:50 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> > On 07/10/2014 12:20 PM, Alvaro Herrera wrote:
> >>> So I guess the only thing left is to issue a NOTICE when said alter
> >>> > takes place (I don't see that on the patch, but maybe it's there?)
> >> That's not in the patch. I don't think we have an appropriate place to
> >> emit such a notice.
> >
> > What do you mean by "don't have an appropriate place"?
> >
> > The suggestion is that when a user does:
> >
> > ALTER INDEX foo_minmax SET PAGES_PER_RANGE=100
> >
> > they should get a NOTICE:
> >
> > "NOTICE: changes to pages per range will not take effect until the index
> > is REINDEXed"
> >
> > otherwise, we're going to get a lot of "I Altered the pages per range,
> > but performance didn't change" emails.
> >
>
> How is this different from "ALTER TABLE foo SET (FILLFACTOR=80); " or
> from "ALTER TABLE foo ALTER bar SET STORAGE EXTERNAL; " ?
>
> we don't get a notice for these cases either
>

I think those are different. They don't rewrite existing data in the
table, but they are applied to new (and updated) data. My understanding is
that changing PAGES_PER_RANGE will have no effect on future data until a
re-index is done, even if the entire table eventually turns over.

Cheers,

Jeff