Instead of the B$-$tree leaves having pointers to data records, the B$-$tree

leaves hold the records themselves. A block can hold ten records, but

on average, a leaf block is $70\%$ full; i$.$e$.,$ there are seven records per leaf

block.

e$)$ The data file is a sequential file, and the B$-$tree is a sparse index, but each

primary block of the data file has one overflow block. On average, the

primary block is full, and the overflow block is half full. However, records

are in no particular order within a primary block and its overflow block.