NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/sys/dec/6526

Text File | 1992-12-20 | 3.4 KB | 76 lines

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From: [e-mail] (Blair Phillips - Digital)
Subject: Re: DEC Design Tools (CDD, DEC repository), are they any good ?
Message-ID: <[e-mail]>
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Organization: Digital Equipment Corporation
References:  <[e-mail]>
Date: Fri, 18 Dec 1992 00:11:23 GMT


In article <[e-mail]>, [e-mail] (Rob J. Nauta) writes:
>
>My boss thinks buying DEC design tools like CDD (Common Data Dictionary
>and DEC repository) will solve his problems concerning database management.
>Is this true, what are your experiences ?
>
Buying tools never solves problems! However, the process you put in place to
solve the problems may be able to make good use of tools.

If used wisely, in a well designed process, CDD/Repositiory is a very valuable
tool.

First, some clarifications:

CDD/Repository is the first implementation of DEC's repository. They are not
separate products.

CDD/Administrator is a management tool for CDD/Repository. It is highly
desirable if you intend to do any extensions to the repository data models.

DECdesign is an analysis/design tool (like Cadre Teamwork or IDE) that uses
CDD/Repository for an object store (on VMS), and can generate data definitions
for CDD/R.

Assumptions:
Operating system is OpenVMS
Database is Rdb/VMS
Programming is done in DEC 3gl languages or a 4gl that supports CDD.

CDD is very useful for managing the data definitions for an enterprise. It can
be used as the common definition store for Rdb and for most common 3gls. I have
used it from COBOL, FORTRAN, Pascal and C. Many of the popular 4gls (eg.Rally,
Powerhouse) can also work with CDD.

This is of particular value on very large projects, or where a large number of
projects share data definitions. One customer site I worked at had close to 100
applications sharing common definitions, and presented interesting coordination
problems. The ability to refer to data definitions in another repository is
very valuable in these cases. You can set up corporate, application and
developer level repositories and inherit definitions form one to another.

Managing the repositories on a large site is a problem in itself, and really
need to be sorted out before you invest the effort to populate the
repositories. If you have a large site, it would be worth getting an
experienced consultant to advise on this.

CDD/Plus V4 had some bad performance problems, and this alienated a lot of
users, particularly those who had moved form earlier versions without changing
their data dictionary structure or management. The performance in
CDD/Repository V5.x is much better, but the need for careful design is still
there.

CDD/Repository will not help at all with other dba problems such as logical and
physical design, database tuning, backup strategies etc. DECdesign and
RdbExpert can help with some of these problems.
--
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Blair Phillips                    [e-mail]
Digital Equipment Corp (Aust) P/L        Phone: [phone]
Canberra, Australia                FAX  : [phone]
{Any opinions expressed are my own, not those of Digital Equipment Corporation}