Why B-Trees Are the Default Database Index
How a database finds one row in ten million without scanning every page. The why behind the B-Tree.
I’m a visual learner, so this channel is built around explaining programming and databases with simple visuals, metaphors, and animations.
This video is meant to explain why database indexes exist, why a simple sequential scan becomes expensive, and why databases often use B-Tree-style indexes instead of just hash maps.
It is not a deep academic breakdown of every index type. The goal is to make the core idea click visually:
sequential scan = check everything
hash index = great for exact lookup
B-Tree index = ordered navigation, great for lookups and ranges
If you’re learning SQL, databases, backend engineering, or system design, this should give you a strong mental model for what an index actually does.