Re: Implement user-defined objects?

Hi Laurent!

I'm not sure I understood you, because I think Data Cartridges are not user defined objects. One of user defined object implementations in Oracle8 database is in fact so called object type which you can reuse in different tables. Object type is consisted of one or more attributes. Attribute can be of predefined datatype (e.g. VARCHAR2, NUMBER) or of another user defined data type. Data collections are another possibility: you can use nested tables and/or varrying arrays. Nested tables are tables stored in one table column which we avoided for years in relational databases. Obviously, to manipulate with object types new capabilities of SQL language must be implemented. Some parts of SQL3 standard are used in Oracle8 database.
However, relationaly oriented people will have to spend significant time for learning object features and new capabilities of SQL that are necessary for manipulation with objects.

One additional problem in Oracle8 environment was that PL/SQL used in client development tools (e.g Forms 5.0) was version 2.3, and that version doesn't support object properties. New generation of tools (Developer 6.0, available since 12 april 99) uses PL/SQL version 8.0, so object capabilities are supported. However, I haven't opportunity to try that new tool.

One of the appearing problems is: how to represent the data stored in e.g. nested table to user??!! Remember,nested table is stored in one outer table column and can have indefinite number of rows for each row of outer (main) table.

I published some papers on this theme (e.g. Advanced Properties of Oracle8 Database) but unfortunatelly only in Croatian language. But, it's possible to find a lot of materials on WWW.

If you have more questions, or you notice that I'm not right, please let me know. My e-mail address is: mario_at_hnb.hr.

Hope this helps,

Mario

Laurent Meurisse <laurent.meurisse_at_ist.lu> wrote in article <37736B9C.90D10ADF_at_ist.lu>...
> Hi,
>
> I was wondering how easy it is, in an object-relational DBMS, to
> developp user-defined objects, like
> - Data Cartridges (Oracle8i)
> - DataBlades (Informix)
> - Extenders (IBM DB2) ?
>
> When you read the white papers of these DBMS vendors, it sounds quite
> easy to extend a relational DBMS with object features, user-defined data
> types, ... But how is it in practice?
>
> Any comments on this?
>
> Thank you,
> Laurent Meurisse
>
> Institut Supérieur de Technologie
> Informatique Appliquée
>
Received on Fri Jun 25 1999 - 21:21:05 CEST