Initially, SQL Developer was considered to be a developer tool that can make the database client connections work with the privileged database objects. Over the years, the Oracle SQL developer tool has been continuously evolving and maturing as a full-fledged product that has largely changed the usage of SQL developer from a user perspective.
One of the major features is the SQL Developer's DBA panel that allows a database administrator to carry out DBA activities with much more ease and supports the 12c database with a multi-tenant architecture and its cloud features fully.
The database instance viewer window is a very useful feature for DBAs who can look at the target database with a 360 degree view. To open the instance viewer, we can use the navigation View | DBA.
We should add the DBA connection (preferably the system connection that we have already defined in the connections navigation pane).
Once the DBA connection is made, open the database status node, click on the database status needed, as shown in the following screenshot:
The information shown in the instance status window might take a while to come up, as shown in the below screenshot. This window is otherwise called as Instance Viewer and we have detailed information about all our database sessions, processes, wait events, CPU, memory, and storage details.
A double-click on each of these graphs will take us to more detailed information. For example, a double-click on the sessions graph will take us to more drill-down information on the database sessions.
Instance viewer is helpful in quickly looking into the activities of a database instance in a 360 degree view.