Re: difference between instance and database name?

Steve-

The difference is, first of all, that the database represents the physical files involved in Oracle - data files, etc. The instance is, of course, the collection of processes and shared memory that manage the database. The listener must distinguish between instances in order to connect you to the right bunch of stuff. The instance opens and manages one-and-only-one database.

And before you finger-wagging nitpick-geeks out there point out the a link allows an instance to manage a remote database, I remind you that it does so vicariously - through a session belonging to the remote instance. Back to the topic...

The idea is that you might have more than one instance on a particular machine and one listener to sort out the connection requests. Moreover, you might be running Parallel Server, which means two or more instances connecting to one database. Listener connects you to the instance, which in turn gets you to the database. Both instances are sharing the same database, so you might have two or more distince instance names and one database name. Thinking about that helps you remember when to user "alter database..." versus "alter system...".

Make sense?

Roger

Roger Snowden
Sr. Systems Engineering Specialist
Oracle Corporation
rsnowden_at_NOTus.oracle.com <-- to reply, remove the obvious

steve_young_at_my-dejanews.com wrote:
>
> What is the difference between instance and database name? I know this is a
> stupid question. But I always got confused.
>
> Thanks.
>
> Steve
>
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Received on Sat Dec 19 1998 - 12:50:27 CST