Re: Few very BASIC Q's - pls not let to die :)

well, I will do my best, others can add....

Rashid Karimov. (rashid_at_haven.ios.com) wrote:

: Hi there folx.

: I have a few Q's about - very basic ones , I think ,
: but I wasn't able to find answers myself ( I do have
: some expirience with different RDBMS ) , albeit I
: tried real hard ( all books on ORACLE we have here
: in NYC were tried ) .
 

: OK.

: 1.
: As I got , one can have more than 1 database , which is
: a _physical stuff and carries tablespaces ( SYSTEM is
: the only one which is created automatically ),tables
: themselves and redo/control files.
 

: Is it possible to have more that 1 database opened in the
: same time on the same computer ( I use ORACLE 7.0.16
: under SOLARIS 2.4) ? How ?

No problem (depending on OS, memory...). You need to do the CREATE DATABASE command, plus a few other things. See Chap. 2 of DBA Manual.

: Can one( the same ) instance serve multiple databases ? Or you have
: to start an instance for every database you want to
: open ?
: The SGA area - does it serve all mounted/opened databases or
: there is a SGA per database ?

I think, basically one SGA per database. Certainly that is the mainstream way to operate.

: What's init****.ora file ? You have to create/customize
: one for every new database ?

Yes, just clone and customize.

: 2.
: The database which is created during the installation -
: does it have any special meaning ? In other words ,
: shoud you _always open/mount it for ORACLE to work ?
: Is it mounted automatically ?
: Help/error messages for different ORACLE binaries -
: are they stored in that database ? Or binaries are
: able to access some files with that stuff w/o actually
: working with ORACLE ?

No, it typically does not have any special meaning. It is not mounted automatically unless, on your OS, the installation process adds the DB startup at the OS level. I think the ORATAB file plays a role in this, I am fuzzy on it, it's been a while.

: 3.
: The oratab file - what's its purpose ? Can one add
: the entries to that file to get new databases be
: opened/mounted automatically ?

yes, I think so, depending on OS.... see above.

: 4.
: When one creates new database/s - does it modifies
: some ORACLE ( system ) tables ?
: In other words - to remove a database - is it enough
: just to remove all associated physical files ? After
: which ORACLE forgets about that database completely ?

I think bringing it down completely (!) and dropping all files (including pesky things you might forget, like ORATAB entries) will cause Oracle to "forget about that database completely". This is tricky because you never know what "uninstall" related garbage may hang around, e.g. a SQLNET DBNAME in an ORACLE.INI file on a few client PC's.

: I'm sorry for these Q's - for some guru they should seem
: really stupid - but I need the answers to get peace in
: my mind :))
 

: Personal E-mail would be appreciated
 

: Rashid
: --
: ------------------
 

: Beyond the horizon of the place we lived when we were young
: In the world of magnets and miracles
: Our thoughts strayed constantly and without boundary
: The ringing of the division bell had begun ...
: -=PF, The Division Bell=-

--
==============================================================
Doug Thomson       Fourth Shift Corp.   (software developer)
(612) 851-1471     Minneapolis, Minnesota   USA