mediumDSA

What is an index and how does it speed up queries?

Q: What is an index and how does it speed up queries?

## Database Indexing An **index** is an auxiliary, sorted data structure that maps **column values → storage pointers**, allowing the database engine to find matching rows without reading the entire table (avoiding sequential table scans). The default index type is a **B-Tree** (Balanced Tree), which organizes keys in a sorted, multi-level hierarchy: Index (B-Tree Key) Table Row Pointer <t

82 views

Understand the problem

Explain indexes.

index

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Stuck? AI Nudge Available

Get a conceptual hint to guide your logic without spoiling the final implementation.

Study the solution

The solution is waiting

Give it an honest attempt first — then compare your thinking with the full walkthrough.

Run the code

SQLIndexing Playground

Join the discussion

Discussion (0)

No responses yet. Be the first to share what you think.

What is a self join?

What do GROUP BY ROLLUP and CUBE do?