Level 2: Data · L2.1 Data models, SQL vs NoSQL, storage engines & indexing
How indexes work (B-trees)
Explain B-tree lookups, composite and covering indexes.
13 min · Pro
What you take away
- A B-tree has a fan-out of hundreds, so 100 million rows are three or four page reads deep — and the upper levels are always cached.
And 3 more inside the class, in Pro.
How the class is laid out
- The problem
- The simple version
- Descending the tree
- Three rules that follow
- Check your understanding