Discuss how the log file (or journal) is a fundamental feature in any recovery mechanism. Explain what is meant by forward and backward recovery and describe how the log file is used in forward and backward recovery. What is the significance of the write-ahead log protocol? How do checkpoints affect the recovery protocol?
What will be an ideal response?
Log file contains before and after-images of updates to the database. Before images can be used to
undo changes to the database (i.e. perform backward recovery); after-images can be used to redo
changes (i.e. perform forward recovery).
You might also like to view...
Which of the following is false?
a. JFrame is a lightweight component. b. JFrame is a subclass of Frame (which is a subclass of Window). c. JFrames have a title bar and a border. d. A JFrame window will look like all other windows displayed on that platform.
Given the declarations below, write a code fragment that allocates a nameless variable for pointer p1 to point to.
``` int *p1, *p2; ```
When you use the Clear Formatting option, Word will automatically apply the Normal style which is the default style
Indicate whether the statement is true or false
Suppose, in a scenario based on a true story, a network computer virus is designed so as soon as it is copied onto a computer, X, it simply copies itself to six of X's neighboring computers, each time using a random file name, so as to evade detection. The virus itself does no other harm, in that it doesn't read any other files and it doesn't delete or modify any other files either. What harm
would be done by such a virus and how would it be detected? What will be an ideal response?