Index Structures

1
Index Structures

• Consider a relation Employees (eid, name, salary,
  age, did) stored as a heap file (unsorted) for
  which the only index is an unclustered index on a
  field called salary.
• 1. If you want to retrieve all records with
  salary gt 50, is using the index always better
  than other alternatives?
• 2. What could be a problem if the index is
  sparse?
• 3. What will you recommend to change to make this
  index useful for both equality search (e.g.,
  salary 25) and range search ( e.g., 10 lt salary
  lt 30)?
• 4. If you need to add one more index on a field
  called name, can both of them sparse?
• 5. Can both of them clustered?