For Oracle, we mount the instance to the database or mount the database to the instance?

From Oracle Docs:

Start the instance, and mount and open
the database. This can be done in
unrestricted mode, allowing access to
all users, or in restricted mode,
allowing access for database
administrators only.

....

To mount a database to a previously
started, but not opened instance, use
the SQL statement ALTER DATABASE with
the MOUNT clause as follows:

ALTER DATABASE MOUNT;

The first part gives me the impression that we are mounting the instance to the database. But the "To mount a database to a previously started, but not opened instance" part makes me think that we are mounting the database to an instance.

What is the correct interpretation when working with Oracle database instances?

We are mounting a database to an instance. See the concepts guide:


The instance mounts a database to
associate the database with that
instance.

One way I've seen it explained (probably here or on SO) is that the instance is the memory structures and processes, and the database is the data on disk. The instance has to have a database associated with it to be able to do anything useful.

StackExchange Database Administrators Q#3647, answer score: 13