Define check point and its impact on data base recovery.                

 Ans:  There could be hundreds of transactions handled per minute, in a large on-line database system. The log for this kind of database consists of a very large volume of information. A scheme called checkpoint is utilized to limit the volume of log information that has to be handled and processed in the event of a system failure including the loss of volatile information. The checkpoint scheme is an extra component of the logging scheme. A checkpoint operation carried out periodically, copies log information onto stable storage. For all transactions active at checkpoint, their identifiers and their database modification actions that at that time are reflected just only in the database buffers, will be propagated to the suitable storage.