Exercise 15.5 Consider the query πA,B,C,D(R ⋈A=CS). Suppose that the projection routine is based on sorting and is smart enough to eliminate all but the desired attributes during the initial pass of the sort and also to toss out duplicate tuples on-the-fly while sorting, thus eliminating two potential extra passes. Finally, assume that you know the following:
R is 10 pages long, and R tuples are 300 bytes long.
1. What is the cost of writing out the final result? (As usual, you should ignore this cost in answering subsequent questions.)
2. Suppose that three buffer pages are available, and the only join method that is implemented is simple (page-oriented) nested loops.
(a) Compute the cost of doing the projection followed by the join.
(b) Compute the cost of doing the join followed by the projection.
(c) Compute the cost of doing the join first and then the projection on-the-fly.
(d) Would your answers change if 11 buffer pages were available?
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