Comparison Selections

Sorted Selection

• perform a linear file scan in the part ahead or behind the specified index, depending on the request.

Unsorted Selection

• For \(A \ge V\) , use index to find the first tuple, then scan relations sequentially from there.
• For \(A \le V\), scan leaf pages for index to find pointers till first entry \(> V\).
• Retrieve record in either case
• This requires an IO per record, which can be larger than a linear file scan.