AIncorrect Answer

An index on cid in Competes will speed query (Y).

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BIncorrect Answer

This index will hasten query (X)

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CCorrect Answer

Neither of the queries mentioned would use such an index.

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DIncorrect Answer

Such an index would expedite query (X).

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EIncorrect Answer

The execution of query (Y) would be accelerated by such an index.

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A B C D E TELL ME NEXT INDEX
 
 

An athletics meeting involves several competitors who participate in a number of events. The database is intended to record who is to take part in which event and to record the outcome of each event. As results become available the winner attribute will be updated with the cid of the appropriate competitor.

		Competitor(cid, name, nationality)
		Event(eid, description, winner)
		Competes(cid, eid)
Competitor
cidnamenationality
01 Pat British
02 Hilary British
03 Sven Swedish
04 Pierre French
Event
eid description winner
01 running 
02 jumping  
03 throwing 
Competes
cid eid
0101
0201
0302
0402
0403

The actual database is to contain several million competitors and nearly one hundred thousand events. The database must be indexed for producing fast results for two particular queries:

  • (X) A list of the names and nationalities of the competitors for a given event where the event description is given.
  • (Y) A list of event descriptions for a given competitor where the cid is given.

Which of the following is not required?

  1. An index on cid in Competes

  2. An index on eid in Competes

  3. An index on name in Competitors

  4. An index on description in Events

  5. An index on eid in Event