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some clarifications in Oracle [message #197769] Thu, 12 October 2006 10:48 Go to next message
sreehari
Messages: 101
Registered: May 2006
Senior Member
Hi all

I have some doubts in Oracle..
can any one pls clarify ...please.

1.Can an instance have more than one database?
2.Can a database server have two instances?

pls bear with me if i did'nt put my questions perfectly.

Thanks

Re: some clarifications in Oracle [message #197771 is a reply to message #197769] Thu, 12 October 2006 10:59 Go to previous messageGo to next message
Mahesh Rajendran
Messages: 10707
Registered: March 2002
Location: oracleDocoVille
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Account Moderator
1.)
No. You create a database, which has logfiles,controlfiles,datafiles etc.
When you start the database, oracle allocates some resources in memory (SGA) and also starts some background process (SMON etc).
This (SGA+bg process) is called as instance, which would uniquely identify and associate itself to a database.

2.)
Yes, but not in the same host.
It is called as RAC (real application cluster).
A single commond database is shared across multiple nodes with one instance per node per database.



Re: some clarifications in Oracle [message #197772 is a reply to message #197769] Thu, 12 October 2006 11:03 Go to previous messageGo to next message
sreehari
Messages: 101
Registered: May 2006
Senior Member
Thanks

Should the instance and database names should be same?
Re: some clarifications in Oracle [message #197773 is a reply to message #197772] Thu, 12 October 2006 11:13 Go to previous message
Mahesh Rajendran
Messages: 10707
Registered: March 2002
Location: oracleDocoVille
Senior Member
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Not essential, as in case of RAC.
You might have a database named PROD.
The ORACLE_SID would be PROD1 in Nod1 and PROD2 in Node2.
In single instance, it is better to have them same. if you are using DBCA to create databases, it will be the same.
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