# One Row in a Billion: B-Trees and Database Indexes

Find one customer by email among a billion rows in a few disk reads, not minutes: why reading every row and a binary search tree are both too slow on disk, and the structure inside nearly every database index, the B-tree.

![Cheat sheet: One Row in a Billion: B-Trees and Database Indexes](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/f21630099940417ca804bdc6d321412d.webp)

- Category: Data Structures
- Level: Freelancer
- Tags: Balanced Tree, B-Tree, data structures, Index (database)
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/ds-b-trees-cheat-sheet