1. Although external hashing generally permits retrievals, insertions, and removals to be performed more quickly than does a B-tree, it does not support such operations as sorted traversals or range...

1. Although external hashing generally permits retrievals, insertions, and removals to be performed more quickly than does a B-tree, it does not support such operations as sorted traversals or range queries. This deficiency is one motivation for multiple indexing.

2. You can have several index fi les for the same data fi le. Such multiple indexing allows you to perform different types of operations efficiently, such as retrieval by name and retrieval by Social Security number.