An Oracle Database consists of at least one database instance and one database. The database instance consists of memory and processes to manage the multitenant container database (CDB). The CDB consists of physical storage structures (data files) and logical data structures (schemas and schema objects).

This diagram shows a single-instance database architecture, which has a one-to-one relationship between the database and the database instance. Multiple single-instance databases can exist on the same server machine. This configuration is useful for running different versions of Oracle Database on the same machine.

An Oracle Real Application Clusters (Oracle RAC) database architecture consists of multiple instances that run on separate server machines with a single shared database. For more information about the Oracle RAC architecture, see Oracle Real Application Clusters 19c Technical Architecture.

The Oracle Net Listener is a database server process that receives incoming connections from client processes, establishes connections to the database instance, and then hands over the client connections to communicate directly with the server processes to fulfill the client requests. The listener for a single-instance database can run locally on the database server or run remotely.

You can use several tools to administer the database, including the following:

• Oracle Data Pump
• Oracle Enterprise Manager
• Oracle Database AutoUpgrade
• Oracle Database Configuration Assistant (DBCA)
• Oracle Recovery Manager (RMAN)
• Oracle Server Control Utility (SRVCTL)
• SQL Developer
• SQL*Loader
• SQL*Plus

• Database Architecture
• Database Instance
• Multitenant Database Architecture