Which two statements are true about checkpointing（）
- AThe checkpoint frequency decreases with the smaller redo log file size.
- BIt ensures that all committed data is written to the data files during normal shutdown.
- CThe frequent full checkpoint in a database can cause the overall degradation of the database performance.
- DIt prompts the Checkpoint （CKPT） process to write data to the data files and redo information to the online redo log files.