Part II: Evaluating Queries with Just Indexes It is sometimes possible to evaluate a particular query using only indexes, without accessing the actual data records. Consider a database with two tables: Pokemon(charName, attack, stamina, cType) Captured(charName, player, difficulty)

Assume three unclustered indexes, where the leaf entries have the form [search-key value, RID]. on Pokemon on Pokemon on Captured

For Questions 9-12, say which queries can be evaluated with just data from these indexes. - If the query can, describe how. - If the query can't, explain why.

Question 9:

SELECT cType, COUNT(charName) FROM Pokemon GROUP BY cType;

Question 10 SELECT pType, difficulty FROM Pokemon, Captured WHERE stamina = 90 AND Pokemon.charName = Captured.charName;

Question 11: SELECT COUNT(DISTINCT stamina) FROM Pokemon WHERE cType = 'Fire';

Question 12: (think carefully about this one!): SELECT charName, AVERAGE(difficulty) FROM Captured GROUP BY charName HAVING COUNT(DISTINCT player) > 1;