The Set Checkpoint Defrag statement is used in conjunction with the Checkpoint statement. Set Checkpoint Defrag sets the threshold for triggering a Checkpoint Defrag.where size specifies the threshold size.When a Checkpoint statement is performed, either as a result of the .log file reaching the limit set by Set Logsize or by the user issuing a Checkpoint statement, the amount of abandoned space in the database data (.data) file is checked. If it is larger than the value of size, a CHECKPOINT DEFRAG, which eliminates the abandoned space, is performed instead of CHECKPOINT.