Introduction to Oracle system processes and main functions

Introduction to Oracle system processes and main functions
Introduction to major Oracle Processes

Data Writing Process (dbwr): responsible for writing changed data from the database buffer cache to the data file

Log write process (lgwr): writes changes in the redo log buffer to the online redo log file.
System Monitoring (smon): Checks Database Consistency and, if necessary, starts database recovery when the database is opened.

Process Monitoring (pmon): clears resources when an Oracle process fails.

Checkpoint Process (ckpt): updates the database status information in control files and data files whenever changes in the buffer cache are permanently recorded in the database.
Archiving process (arcn): backs up or archives a full log group during each log switch.

Job scheduler (cjq): responsible for scheduling and execution of jobs defined in the system to complete some predefined work.
Restore process (reco): to ensure the consistency of distributed transactions. In distributed transactions, either commit or rollback at the same time;

The following figure shows the main processes of Oracle.

In the middle of this figure, it is SGA. The top part is the RECO, PMON, and SMON processes. The two-way arrows indicate the communication between processes and instances. The lower left side is the DBW0 and LGWR processes. The two processes communicate with the data cache area and the redo log buffer, and access the data files and redo log files respectively.