Q2. Give the optimal estimate for the disk-IO cost of r JOINA-B S using (2.a) Sort-merge join, assuming that the two relations are sorted on the join attributes and r's join

attribute is a key for r. (2.b) Block nested loop join Assume r has 2,000 tuples with 20 tuples per block; s has 4,000 tuples with 4 tuples per block; and the main memory buffer for this operation is 22 blocks.