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Home -> Community -> Usenet -> c.d.o.server -> Re: Question about instances
On Wed, 23 Jun 1999 17:48:08 GMT, sergey_s_at_my-deja.com
wrote:
>I am a bit confused about server/database instances.
>Is server instance the same as database instance?
No. Technically, an "instance" is a set of Oracle background processes, such as DBWR, LGWR, and so forth, plus a shared memory area known as the SGA. The "database", on the other hand, is technically just the files. You can start an instance without opening a database. This is not much different than starting Microsoft Word without opening a file.
>In
>the book I am reading the two wordings seem to refer
>to the same thing sometimes and two different things
>at other times.
Lot's of times people aren't too precise in their use of these terms. People talk about "starting" a database, when in fact you "start" an instance and "open" a database. A book should do better, but I'm not surprised that it does not.
One other piece of info that might help you. Typically, you have one instance operating on one database. That probably leads people to confuse the two terms. That changes if you are running Oracle Parallel Server. Under Parallel Server, you can have many instances all operating on one database.
By the way, what book is it that you are reading?
Jonathan
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