Most developers know that adding an index speeds up queries. But slapping a basic index on every column you filter by is a recipe for bloated storage, slower writes, and no real performance gain. The real power comes from choosing the right type of index for the job . In this article, we'll go beyond the basics and explore three advanced indexing strategies: partial indexes , composite indexes , and covering indexes . Each solves a different class of performance problem, and knowing when to reach for each one separates good database work from great database work. We'll use PostgreSQL throughout, but these concepts apply (with some syntax variation) to MySQL, SQL Server, and other major databases. The Setup: An E-Commerce Orders Table Let's ground everything in a realistic scenario.…