In this article we are going to see Oracle Checkpoint Background Process.
- Checkpoint Process is a background process that, at specific times,starts a checkpoint request by messaging database writer process to begin writing dirty buffers.On Completion of individual checkpoint requests,chkpt updates datafile headers and controlfile to record the most recent checkpoint
- A checkpoint is an operation that Oracle performs to ensure data file consistency. When a checkpoint occurs, Oracle ensures all modified buffers are written from the data buffer to disk files.
- Checkpoint checks every three seconds to see whether the amount of memory exceeds the value of the PGA_AGGREGATE_LIMIT parameter,and if so,takes action.
- CHKPT can run as a thread or an operating system process.In addition to database instances,chkpt also runs on ASM instance
Checkpoint automatically occurs at:
1.Checkpoint automatically occurs at a log switch.
2.When we will specify the parameter fast_start_mttr_target=<No of Seconds>.
3.When Normally forced by the Database Administrator.
4.If the datafile is offline checkpoint will occur.
5.Consistent database shutdown
6.ALTER SYSTEM CHECKPOINT statement
7.ALTER DATABASE BEGIN BACKUP statement.
- The CKPT process does not write blocks to disk; DBWn always performs that work. The statistic DBWR checkpoints displayed by the System_Statistics monitor in Enterprise Manager indicates the number of checkpoint requests completed.
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