Database Indexing 101: Optimizing Your Queries

Anatomy of an Index

Think of an index like the index at the back of a textbook. Instead of reading every page to find "Photosynthesis", you look it up and go straight to page 42.

B-Trees

Most relational databases use B-Trees. They keep data sorted, allowing for O(log n) lookups instead of O(n) full table scans.

CREATE INDEX idx_published_created 
ON Post(published, createdAt DESC);

Always check your EXPLAIN ANALYZE output!