Indexing and Hashing:
Indexing mechanisms used to speed up access to desired data.E.g., author catalog in library Search Key – attribute or set of attributes used to look up records in a file.An index file consists of records (called index entries) of the form
Index files are typically much smaller than the original file Two basic kinds of indices:
Ordered indices: search keys are stored in sorted order Hash indices: search keys are distributed uniformly across “buckets” using a “hash function”.
Index Evaluation Metrics:
Access types supported efficiently. E.g.,records with a specified value in the attribute or records with an attribute value falling in a specified range of values (e.g. 10000 < salary < 40000)