6. Consider the join r▷s of two relations r and s whose common attribute set is {A}. Physically, r is stored on 25 block

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6 Consider The Join R S Of Two Relations R And S Whose Common Attribute Set Is A Physically R Is Stored On 25 Block 1 (74.01 KiB) Viewed 31 times

6. Consider the join r▷s of two relations r and s whose common attribute set is {A}. Physically, r is stored on 25 blocks and s on 21 blocks on the disk, tuples in both relations are unordered. Assume that the buffer pool allocated for carrying out the join has 3 frames. Compare block nested-loop join against merge join in facilitating r s by analyzing their I/O costs. The I/Os for exporting the final joined results to the disk is called the reporting cost, which shall be excluded from the calculation of the I/Os of r▷s, because the reporting costs of both nested-loop join and merge join cancel each other out in the comparison. Specifically, (a) Compute the # of I/Os, excluding the reporting cost, engaged by block nested-loop join. [3 marks] (b) Compute the # of I/Os, excluding the reporting cost, engaged by merge join in the worst-case and best-case scenarios, respectively. A scenario is an instantiation of the tuples in r and s, especially on attribute A. [5 marks]