How the records are changed

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How would your answers to Exercise 10.7 change if attribute a is not a candidate key for R? How would they change if we assume that records in R are sorted on a?

Exercise 10.7

Consider a relation R(a, b, c, d) containing 1,000,000 records, where each page of the relation holds 10 records. R is organized as a heap file with dense secondary indexes, and the records in R are randomly ordered. Assume that attribute a is a candidate key for R, with values lying in the range 0 to 999,999. For each of the following queries, name the approach that would most likely require the fewest I/Os for processing the query. The approaches to consider follow:

? Scanning through the whole heap file for R.

? Using a B+ tree index on attribute R.a.

? Using a hash index on attribute R.a.

The queries are:

1. Find all R tuples.

2. Find all R tuples such that a

3. Find all R tuples such that a = 50.

4. Find all R tuples such that a > 50 and a

Reference no: EM131210942

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