Re: Creating Database/admin questions

anderson_at_dtracy.enet.dec.com (Marianne Anderson) writes:

>How often are databases created? Is there usually just one database on a
>system, or can just about anyone create one? I get the impression that on Unix
>type systems, very few people have the privilege to be able to create a
>database. Is this the norm?

There seems to be a lot of confusion about this, especially with Oracle 7. (I suspect it is more confusing for people coming from a PC environment, such as those to whom a database means something like dBase, FoxPro, or Access, since multiuser capabilities and requirements are generally nonexistant there.)

Under Oracle 7, a 'database' refers to a full set of tables, data dictionaries, users, roles, etc. Usually the term 'database' and 'instance' (referring to the suite of Oracle programs that actually access the data) are somewhat interchangeable, since each database is usually accessed by only one instance and vice-versa. (Ignoring distributed and multi-processor issues.)

To make matters even more confusing, there is also the concept of 'tablespaces' which refers to a collection of datafiles for the storage of such things as tables and indexes, but this is more of a 'physical storage' issue than a logical design one.

Do you really need TOTALLY independent 'databases' here, or just separate collections of tables that will come and go as needed? Since the creation of a new database involves not only the allocation of disk space but also memory and processor resources, not to mention all the database and user definitions needed to actually USE data, it is not unreasonable for the ability to create a new database to be severely restricted.

This is a somewhat simplified explanation, of course. :-)

---
Michael Nolan, Sysop for the DBMS RoundTable on GEnie
nolan_at_notes.tssi.com, dbms_at_genie.geis.com
(posted from nolan_at_helios.unl.edu)