Обсуждение: recursive views

I had some time during vacation to thing about postgresql. And here's the
feature I'd really like to see. This one would put us miles in front of all
others: recursive view definitions.

Just one short example:

There is that well-known parent relation: par (parent, child). The view anc
now should list all ancestors:

create view anc as
    select parent as ancestor, child as person from par
    union
    select anc.ancestor as ancestor, par.child as person
    from anc, par
    where anc.person = par.parent;

What do you guys think of this idea? How much work would it be to implement
it?

Michael
--
Dr. Michael Meskes, Project-Manager    | topsystem Systemhaus GmbH
meskes@topsystem.de                    | Europark A2, Adenauerstr. 20
meskes@debian.org                      | 52146 Wuerselen
Go SF49ers! Go Rhein Fire!             | Tel: (+49) 2405/4670-44
Use Debian GNU/Linux!                  | Fax: (+49) 2405/4670-10

>
> I had some time during vacation to thing about postgresql. And here's the
> feature I'd really like to see. This one would put us miles in front of all
> others: recursive view definitions.
>
> Just one short example:
>
> There is that well-known parent relation: par (parent, child). The view anc
> now should list all ancestors:
>
> create view anc as
>     select parent as ancestor, child as person from par
>     union
>     select anc.ancestor as ancestor, par.child as person
>     from anc, par
>     where anc.person = par.parent;
>
> What do you guys think of this idea? How much work would it be to implement
> it?

You want views of UNION's.  That is not hard to do.


--
Bruce Momjian                          |  830 Blythe Avenue
maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
  +  If your life is a hard drive,     |  (610) 353-9879(w)
  +  Christ can be your backup.        |  (610) 853-3000(h)

>
> I had some time during vacation to thing about postgresql. And here's the
> feature I'd really like to see. This one would put us miles in front of all
> others: recursive view definitions.
>
> Just one short example:
>
> There is that well-known parent relation: par (parent, child). The view anc
> now should list all ancestors:
>
> create view anc as
>     select parent as ancestor, child as person from par
>     union
>     select anc.ancestor as ancestor, par.child as person
>     from anc, par
>     where anc.person = par.parent;
>
> What do you guys think of this idea? How much work would it be to implement
> it?

Ah, you want views of UNION's, and want to specify the view in the
query.  Yikes, no idea on how hard that would be.

--
Bruce Momjian                          |  830 Blythe Avenue
maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
  +  If your life is a hard drive,     |  (610) 353-9879(w)
  +  Christ can be your backup.        |  (610) 853-3000(h)