If you were about to create an index on a relation, what considerations would guide your choice? Discuss:
1. The choice of primary index.
2. Clustered versus unclustered indexes.
3. Hash versus tree indexes.
4. The use of a sorted ?le rather than a tree-based index.
5. Choice of search key for the index. What is a composite search key, and what considerations are made in choosing composite search keys? What are index-only plans, and what is the in?uence of potential index-only evaluation plans on the choice of search key for an index?