Обсуждение: Support for persistant objects in PostgreSQL?

Hi,

Can you have persistant objects in PostgreSQL? In
Oracle you can have create Object types. e.g
create type ADDRESS as object  (street_name     VARCHAR2(30),   house_no        NUMBER);
In Oracle you can even have references to these
objects from other tables.

Is persistant objects and references to these objects
supported in PostgreSQL? If so can anyone point me to
the documentation for these?

Thanks,
Suresh


    
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On Aug 2, 2004, at 2:08 AM, Suresh Tri wrote:

> Hi,
>
> Can you have persistant objects in PostgreSQL? In
> Oracle you can have create Object types. e.g
> create type ADDRESS as object
>    (street_name     VARCHAR2(30),
>     house_no        NUMBER);
> In Oracle you can even have references to these
> objects from other tables.
>

create type ADDRESS as (street_name varchar(30),house_no int
);

should be about the same.

You can write stored proc's to return setof address if you want.
Not sure if there are other things that make oracle objects special.

There is even support for creating your own truely unique type where 
you need to write your inputter, outputter and comparison functions.  
That can allow you to natively support some proprietary data format you 
may have.

--
Jeff Trout <jeff@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/

Suresh,

> Is persistant objects and references to these objects
> supported in PostgreSQL? If so can anyone point me to
> the documentation for these?

These structures are usually known as "Composite Types", although they have a 
different, less intuitive name in the SQL99 standard which escapes me at the 
moment.   "Persistant Objects" is an Oracle-ism which is why you're having 
trouble finding help on it.

Currently 7.4 PostgreSQL 7.4 supports the creation of such types and use of 
them in Functions and queries.  However, using them as a table column will 
not be supported until the next PostgreSQL version, coming soon.   

I don't reccomend using them at any time, though ...

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

Josh Berkus wrote:
> I don't reccomend using them at any time, though ...

Just curious: why not?

Merlin

On Mon, 2 Aug 2004, Josh Berkus wrote:

> Suresh,
>
>> Is persistant objects and references to these objects
>> supported in PostgreSQL? If so can anyone point me to
>> the documentation for these?
>
> These structures are usually known as "Composite Types", although they have a
> different, less intuitive name in the SQL99 standard which escapes me at the
> moment.   "Persistant Objects" is an Oracle-ism which is why you're having
> trouble finding help on it.
>
> Currently 7.4 PostgreSQL 7.4 supports the creation of such types and use of
> them in Functions and queries.  However, using them as a table column will
> not be supported until the next PostgreSQL version, coming soon.

Is this much different (and how?) then using inheritance?  CREATE TABLE vs 
CREATE TYPE ... but looking at the example he provided, that was my first 
thought ...

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org           Yahoo!: yscrappy              ICQ: 7615664

Merlin,

> Just curious: why not?

Because it's non-atomic data, which violates normalization and makes 
maintenance and data cleaning a royal pain.  Also, you'd still need to write 
your own operators to be able to do comparisons.

-- 
-Josh BerkusAglio Database SolutionsSan Francisco