Which three statements are true regarding an Oracle instance? (Choose three)
A.
One instance is associated with only one database.
B.
Multiple database instances can run on one computer.
C.
Only one database instance can run on one computer.
D.
One instance can be associated with multiple databases.
E.
A database instance is created based on the information in the control file.
F.
A database instance is created based on the information in the SPFILE file.
Explanation:
Note:
https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1631683800346891854
Defining Database and Instance
There are two terms that, when used in an Oracle context, seem to cause a great deal of confusion: ‘instance’ and ‘database”. In Oracle
terminology, the definitions of these terms are as follows:
* Database: A collection of physical operating system files or disk. When using Oracle 10g Automatic Storage Management (ASM) or RAW
partitions, the database may not appear as individual separate files in the operating system, but the definition remains the same.
* Instance: A set of Oracle background processes/threads and a shared memory area, which is memory that is shared across those
threads/processes running on a single computer. This the place to maintain volatile, nonpersistent stuff (some of which gets flushed to disk).
A database instance can exist without any disk storage whatsoever. It might not be the most useful thing in the world, but thinking about it
that way will definitely help draw the line between the instance and the database.
The two terms are sometimes used interchangeably, but they embrace very different concepts. The relationship between them is that a database
may be mounted and opened by many instances. An instance may mount and open a single database at any point in time. In fact, it is true to say
that an instance will mount and open at most a single database in its entire lifetime!