Re: What is this thing that is called a "Data Dictionary?"

FWIW, in my (admittedly limited) experience, a Data Dictionary is a
metatdata entity or concept, generated by the RDBMS. It's essentially a
single source describing the schema - tables, relationships, views,
types, functions, triggers, stored procedures, etc. The equivalent in
PGSQL *is* the schema, based on looking at the structure of a DB using
PGADMINIII.

The Data Dictionary can be stored as a separate entity within an RDBMS's
structure, or it can be stored within the schema itself, as I believe it
to be in PGSQL.

Please correct me if I'm wrong... ;)

The DBA would more likely use the Data Dictionary as a tool to help
document the database, generate ERD's, etc. as opposed to the DBA
creating the Data Dictionary as one form of documenting the database.

I should go dig up my old dusty SQL97 manual - I think data dictionary
may be mentioned there.

-----Original Message-----
From: pgsql-novice-owner(at)postgresql(dot)org
[mailto:pgsql-novice-owner(at)postgresql(dot)org] On Behalf Of Richard Broersma
Jr
Sent: Wednesday, May 02, 2007 3:29 PM
To: Jasbinder Singh Bali
Cc: Novice Postgresql-list
Subject: Re: [NOVICE] What is this thing that is called a "Data
Dictionary?"

Thanks Jas for the description, it is very helpful.

Regards,
Richard Broersma Jr.

--- Jasbinder Singh Bali <jsbali(at)gmail(dot)com> wrote:

> AFAIK, data dictionary is just the metadata (read only set) that
> contains the definitions of data elements like tables, views,
> trigggers, SPs, roles, general DB structuring, space allocation
> methodology of the DB etc (i mean any data element inside the DB).
>
> It can be viewed as a simple read only file defining the basic
> structure of the database actually, in lay men terms.
>
> Also most of the times, i've observed that its hidden from the users
> even though its read only. Only DBA should have access to such kind of

> file in secured systems. Thats how we implement it in our projects out
here.
>
> Bookkeeping is just synonymous to a data dictionary that would not
> contain the actual data but would essentially explain the way data
> would be managed and how.
>
> I hope this helps.
>
> Thanks,
> ~Jas
>
> On 5/2/07, Richard Broersma Jr <rabroersma(at)yahoo(dot)com> wrote:
> >
> > Many of the ERD and SQL books that have have read refer to a data
> > dictionary. However, I seem to be missing the point of what it
> > acuatally is. IIRC, some books refer to it as a kind of document
> > created by a DB designer, and other suggest that it is a kind of
> > RBDMS created metadata.
> >
> > Can anyone please offer a consise description or provide a link to
> > that describes what it is?
> > Also, how is this information useful to a DBA?
> >
> > Thanks for the help!
> >
> > Regards,
> > Richard Broersma Jr.
> >
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