Oracle Database relies on several background processes to perform various tasks and maintain the health and performance of the database. Here are some of the key background processes in Oracle Database:
1. DBWn (Database Writer): This process writes data from the database buffer cache to the physical data files on disk.
2. LGWR (Log Writer): This process writes redo log entries to disk and ensures that transactions are durable.
3. PMON (Process Monitor): This process monitors other background processes and sessions, and cleans up resources after a process or session terminates abnormally.
4. SMON (System Monitor): This process performs various tasks to maintain the health of the database, such as cleaning up temporary segments and freeing up unused space.
5. CKPT (Checkpoint): This process ensures that all dirty buffers are written to disk and updates the control file and data file headers.
6. RECO (Distributed Transaction Recovery): This process recovers distributed transactions that were left in an uncertain state due to a network or system failure.
7. MMON (Manageability Monitor): This process collects data for Automatic Workload Repository (AWR) and other performance-related features.
8. MMNL (Manageability Monitor Light): This process manages the automatic maintenance tasks such as Automatic Optimizer Statistics Collection, Automatic Segment Advisor, and Automatic SQL Tuning Advisor.
9. MMAN (Memory Manager): This process manages the system's shared memory, including the database buffer cache.
10. DIA0 (Diagnostic Process): This process is responsible for diagnosing and resolving database and instance issues.
These background processes work together to ensure that the database is available, reliable, and performing optimally. By monitoring these processes, database administrators can identify and resolve issues quickly, and ensure that the database meets the performance and availability requirements of the organization.