The total cost of retrieving records in sorted order using an unclustered B+ tree is (P = average number of records per data page, N = number of data pages, F = ratio of the size of a data entry to the size of a data record)
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Correct answer: B. (F + P) × N
Explanation
Scanning the leaf level costs F·N page I/Os. In the worst case each of the P·N records needs a separate I/O because the index is unclustered. Total = F·N + P·N = (F + P)·N.More Database Management Systems questions
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