Let relations r_{1}(A, B, C) and r_{2}(C, D, E) have the following properties: r_{1} has

20,000 tuples, r_{2} has 45,000 tuples, 25 tuples of r_{1} fit on one block, and 30

tuples of r_{2} fit on one block. Estimate the number of block transfers and seeks

required using each of the following join strategies for r_{1} ⋈ r_{2}: Block nested-loop join.

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Step 1Block nested-loop join:The “r1” needs (20000/25)=800 blocks and “r2” needs (45000/30)=1500 blocks.Let assume “M” pages of memory. If “M” is greater than 800, the join can easily done in 1500+800 disk accesses, using even plain nested loop join.So one can consider only the case where “M” less than or equal to 800 pages.Step 2If, “r1” is the outer relation the user need,[800/M-1]*1500+800 disk accesses.If, “r2” is the outer relation the user need,[1500/M-1]*800+1500 disk accesses. ...