A checkpoint is used to ensure consistency in the database; during this operation, all data files are synchronized with the data blocks in memory.
The process responsible for signaling a checkpoint is the
CKPT process, which signals the
DBWn processes to write the dirty (modified) buffers from database buffer cache in memory to the data files.
During this operation data, file headers and control files are updated to store the last System Change Number (SCN), to ensure data block consistency.
In this recipe, we will see how to tune checkpoints in an Oracle database, to optimize all these write operations involved in checkpoints, balancing the trade-off between the redo log size and recovery time, in case of instance failure.