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.