Re: On partitioning

On Tue, Dec 9, 2014 at 7:21 PM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:
>
> Amit Kapila wrote:
> > On Tue, Dec 9, 2014 at 1:42 AM, Robert Haas <robertmhaas(at)gmail(dot)com>
wrote:
> > > On Mon, Dec 8, 2014 at 2:56 PM, Andres Freund <andres(at)2ndquadrant(dot)com>
> > wrote:
> > > >> I don't think that's mutually exclusive with the idea of
> > > >> partitions-as-tables. I mean, you can add code to the ALTER TABLE
> > > >> path that says if (i_am_not_the_partitioning_root) ereport(ERROR,
...)
> > > >> wherever you want.
> > > >
> > > > That'll be a lot of places you'll need to touch. More
fundamentally: Why
> > > > should we name something a table that's not one?
> > >
> > > Well, I'm not convinced that it isn't one. And adding a new relkind
> > > will involve a bunch of code churn, too. But I don't much care to
> > > pre-litigate this: when someone has got a patch, we can either agree
> > > that the approach is OK or argue that it is problematic because X. I
> > > think we need to hammer down the design in broad strokes first, and
> > > I'm not sure we're totally there yet.
> >
> > That's right, I think at this point defining the top level
behaviour/design
> > is very important to proceed, we can decide about the better
> > implementation approach afterwards (may be once initial patch is ready,
> > because it might not be a major work to do it either way). So here's
where
> > we are on this point till now as per my understanding, I think that
direct
> > operations should be prohibited on partitions, you think that they
should be
> > allowed and Andres think that it might be better to allow direct
operations
> > on partitions for Read.
>
> FWIW in my original proposal I was rejecting some things that after
> further consideration turn out to be possible to allow; for instance
> directly referencing individual partitions in COPY. We could allow
> something like
>
> COPY lineitems PARTITION FOR VALUE '2000-01-01' TO STDOUT
> or maybe
> COPY PARTITION FOR VALUE '2000-01-01' ON TABLE lineitems TO STDOUT
>
or
COPY [TABLE] lineitems PARTITION FOR VALUE '2000-01-01' TO STDOUT
COPY [TABLE] lineitems PARTITION <part_1,part_2,> TO STDOUT

I think we should try to support operations on partitions via main
table whereever it is required.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com