Consider a relation , and the following frequency distribution for attribute based on a equi-width histogram.

• [0-20): 20
• [20-40): 20
• [40-60): 40
• [60-80): 30
• [80-100): 10
• [100-120): 4

what is the estimated size in terms of number of tuples of the relation

When sorting very large data sets that do not fit in memory, what is generally the primary performance bottleneck?

Consider relations R(A,B,C) and S(C,D,E).  R has 20,000 tuples and S has 45,000 tuples. 25 tuples of R fit on one block, and 30 tuples of S fit on one block. Assuming that the buffer pool has more than 800 frames, what is the minimum number of block transfers that will be required to compute R S.

In external sorting, which factor most critically limits overall performance when dealing with huge files?

During external merge sort, the dominant cost is associated with:

A file with 50,000 pages is sorted using external merge sort with 101 buffers. How many merge passes (after initial run creation) are necessary if up to 100 runs can be merged simultaneously?

Consider relations R(A,B,C) and S(C,D,E). R has 20,000 tuples and S has 45,000 tuples. 25 tuples of R fit on one block, and 30 tuples of S fit on one block. Further, S.C is the primary key in relation S, and there is clustering B+tree index on S.C with height 4. How many block transfer would an index nested loop join incur?

In external merge sort, the performance of the merge phase is independent of the number of available buffers.

A file has 8,000 pages, and 81 buffer pages are available. What is the least number of merge passes required in external merge sort?