-
Title
What is the meaning of Background Activity in Oracle? -
Description
What means "Background Activity" in Oracle?
-
Resolution
In Oracle, Background Activity refers to processes and tasks that run in the background of the database environment to support its overall operation. These activities are typically handled by background processes and threads that do not require direct interaction with users but are essential for database performance, resource management, and maintenance.
Key aspects of Background Activity in Oracle include:
1. Background Processes:
Oracle Database relies on several background processes to maintain its operations, such as:
- DBWn (Database Writer): Responsible for writing modified data from the buffer cache to the data files.
- LGWR (Log Writer): Writes redo log entries from the redo log buffer to the online redo log files.
- CKPT (Checkpoint): Updates the data files and control files to reflect the current point in time of the database.
- SMON (System Monitor): Performs crash recovery, cleans up temporary segments, and manages other recovery-related tasks.
- PMON (Process Monitor): Cleans up after failed user sessions and processes.
- ARCH (Archiver): Archives the redo logs to ensure recovery and to manage redo log history.
2. Maintenance Tasks:
These include periodic database maintenance operations such as:
- Automatic Storage Management (ASM): Manages the storage of database files in a distributed manner.
- Statistics Gathering: Oracle automatically gathers database statistics (like table and index statistics) that help optimize query performance.
- Undo Management: Oracle manages undo information for transaction rollback and consistency.
3. Performance Monitoring:
Oracle tracks and logs various performance metrics, like CPU and memory usage, and identifies slow-running queries or database performance issues.
4. Scheduler Jobs:
Oracle Scheduler allows automated background tasks to run, such as database jobs for data purging, backups, and custom maintenance.
5. Background Threads in RAC (Real Application Clusters):
In Oracle RAC environments, background activity also includes coordination between instances through background threads to maintain data consistency and synchronization across nodes.
These background activities are critical for database reliability, performance optimization, and ensuring data integrity and availability. Although they are not directly visible to the end-users, they are integral to the smooth operation of the Oracle Database system.
For more details of the Oracle background processes please see the Oracle Concepts documentation, for example:https://docs.oracle.com/en/database/oracle/oracle-database/21/refrn/background-processes.html