How many bytes will a S9(8) COMP field occupy ?

What is binary search?

Search on a sorted array. Compare the item to be searched with the item at the center. If it matches, fine else repeat the process with the left half or the right half depending on where the item lies.

What is the mode in which you will OPEN a file for writing?

OUTPUT, EXTEND

What should be the sorting order for SEARCH ALL?

It can be either ASCENDING or DESCENDING. ASCENDING is default. If you want the search to be done on an array sorted in descending order, then while defining the array, you should give DESCENDING KEY clause. (You must load the table in the specified order).