Which statements are true about checkpointing（）

A. The checkpoint frequency decreases with the smaller redo log file size.
B. It ensures that all committed data is written to the data files during normal shutdown.
C. The frequent full checkpoint in a database can cause the overall degradation of the database performance.
D. It prompts the Checkpoint （CKPT） process to write data to the data files and redo information to the onlineredo log file