Indexing Structures for Files: Chapter 14 Quiz

Index Fundamentals

• An ordered index is a data structure that facilitates efficient retrieval of specific records from a file, based on the ordering of a specific field (key).
• A single-level index is used to speed up the retrieval of records from a file, by providing a quick way to locate specific records.

Index Specification

• An index is usually specified by the field(s) on which it is built, and the type of index (e.g., ordered, dense, sparse).

Access Path and Index

• An access path on the field represents a way to access the records of a file, using the index.

Index vs. Linear Search

• An ordered index is generally faster than a linear search, as it allows for direct access to specific records, rather than having to scan the entire file.

Index Characteristics

• A true statement about indexes is that they can be used to speed up retrieval of specific records from a file.
• A dense index has an entry for every key value in the index, allowing for direct access to every record in the file.
• A primary index is defined on the primary key of a file, and is used to provide a unique identifier for each record.

Search Options

• When both the data file and the index file are ordered, a binary search is a better option, as it can take advantage of the ordering to quickly locate specific records.
• A sparse (or nondense) index has entries for only some of the key values in the index, and is used when the index is very large or when the key values are widely scattered.