Database Indexing

overview

Summary

Database indexing is a technique used by databases to speed up data retrieval. Indexes are auxiliary data structures (like B-trees or hash tables) that let the database find rows without scanning entire tables. They improve read performance for lookups, joins, sorting, and grouping, at the cost of extra storage and slower writes due to maintenance. Effective indexing requires understanding workload patterns, data distribution (selectivity), and how query optimizers use indexes.