Re: Storing query language in relations
Date: Wed, 02 Oct 2002 22:38:37 GMT
Message-ID: <NzKm9.306$MV.13285_at_newsc.telia.net>
> > Are there DBMSs where you can "create" new tables, views, indexes,
> > constraints, etc. just by inserting into the appropriate system
> > tables? So the DDL becomes redundant?
>
> I also thought about it ~yr ago: it is certainly a nice idea. DBA have
> to learn only catalog schema, no stupid DDL.
Perhaps I'm missing stuff at beginning of this thread, but isn't DDL actually to be seen as a *good* thing?
By inserting stuff directly into catalog, you make that "DDL" highly product specific. And DDL it is, although in the form of INSERT statements. All current RDBMS's that I know of have their own layout of the system catalog.
ANSI has defined the INFORMATION_SCHEMA view, but these are but views of the actual system tables. ANSI SQL has defined the DEFINTION_SCHEMA tables, but this is, even in the ANSI papers, to be seen as an imaginary set of system tables, for the sake of defining the INFORMATION_SCHEMA views (my own words). I know of no product that has actually implemented the DEFINITION_SCHEMA tables (although I wouldn't be awfully surprised if Ocelot has).
Also, at least MS SQL Server has to do other stuff when you do DDL. For
example:
First, you have several tables. You have one catalog table for the table
existence. And another for column existence. And possible also for the
physical characteristics (where to start a scan, for instance).
Second, initial space allocation probably has to take place. Agreed, this
could be handled by a constraint of some sort, and above could be taken care
of by a deferred constraint. IMO, this wouldn't buy us much, though.
-- Tibor Karaszi "Mikito Harakiri" <mikharakiri_at_yahoo.com> wrote in message news:bdf69bdf.0210021407.39e664b9_at_posting.google.com...Received on Thu Oct 03 2002 - 00:38:37 CEST
> pbrazier_at_cosmos-uk.co.uk (Paul) wrote in message
news:<51d64140.0210020857.278ac3ba_at_posting.google.com>...
> > Are there DBMSs where you can "create" new tables, views, indexes,
> > constraints, etc. just by inserting into the appropriate system
> > tables? So the DDL becomes redundant?
>
> I also thought about it ~yr ago: it is certainly a nice idea. DBA have
> to learn only catalog schema, no stupid DDL.