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Consider the following expression OstuID=6661 Semester=f154Grade=A(Transcript)
Suppose the following access paths are available
• An unclustered/unintegrated hash index on Studi D
• An unclustered/unintegrated hash index on Semester
• An unclustered/unintegrated hash index on Grade .
Which of these access paths has the best selectivity, and which has the worst?
Compare the selec- tivity of the worst access path (among the three above) to the selectivity of a file scan.