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

I think you're right.

I also think that the equivalent in PGSQL may be the information_schema.
That's what MySQL is trumpeting that they've added to their structure
that is the same thing as a data dictionary.

It makes sense - information_schema is a standard SQL thing, that was
introduced back with SQL92. Oracle uses information_schema too but has
their own set of "data dictionary" views that apparently are more
comprehensive ways to access the database's metadata.

Looking at PGSQL's information_schema schema, it does have a lot of that
kind of thing.

I wonder if pg_catalog and pg_toast also are part of the PGSQL "data
dictionary" implementation...

________________________________

From: Jasbinder Singh Bali [mailto:jsbali(at)gmail(dot)com]
Sent: Wednesday, May 02, 2007 4:00 PM
To: Jim Stalewski
Cc: Richard Broersma Jr; Novice Postgresql-list
Subject: Re: [NOVICE] What is this thing that is called a "Data
Dictionary?"

I think data dictionary is automatically build by the DB.
Don't think that its a manual task.
Meta data is always build up automatically by the system intelligently.
Correct me if I'm wrong.

~Jas

On 5/2/07, Jim Stalewski <JStalewski(at)visalighting(dot)com> wrote:

I just went to wikipedia. That's what they say - a data
dictionary is
metadata, and they say that within a DBMS it's represented as a
set of
read-only tables and views.
http://en.wikipedia.org/wiki/Data_dictionary

They seem to indicate it's something that you build, though, not
something generated by the RDBMS.

Innnteresting...

-----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.
> >
> > ---------------------------(end of
> > broadcast)---------------------------
> > TIP 3: Have you checked our extensive FAQ?
> >
> > http://www.postgresql.org/docs/faq
<http://www.postgresql.org/docs/faq>
> >
>


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