Grokking Database Fundamentals for Tech Interviews

What the course covers

The course page lists 12 chapters, 64 lessons and 51 quiz questions, with about 10 hours of study time, at beginner level. The chapters run in this order:

1. Introduction to database systems
2. Data storage in a DBMS: file organisation, page layout, compression and encoding
3. Indexing: single-level, tree-based and hash-based indexes, and Bloom filters, with what each costs on write
4. Transaction management: ACID taken one property at a time
5. Concurrency control: optimistic and pessimistic, lock-based, timestamp-based and multiversion concurrency control (what PostgreSQL and Oracle actually use)
6. Distributed databases, partitioning and sharding, and how a query is processed across machines
7. Replication and consistency models, including the CAP theorem stated in a way you can apply
8. Consensus and leader election
9. Recovery and fault tolerance: write-ahead logging, checkpointing, failover, redundancy and mirroring
10. NoSQL databases: key-value, document, column-family, wide-column and graph stores
11. Advanced topics and emerging trends
12. Database design case studies: Quora, TikTok, Airbnb and Snapchat

Each chapter ends with a quiz.

Ratings and learners

As of September 2026 the course page shows a rating of 4 out of 5 from 288 ratings and 2,677 learners. It was first published in November 2024 and updated within the last month.

Why it matters for system design

Many design answers include a line like "I would use a NoSQL database here" without a reason. This course gives you the reasons: access patterns, consistency needs, write volume and how indexes, isolation levels and replication behave. That turns a database choice into a statement you can defend when the interviewer asks "why?".

How to get the most from it

• Run small experiments alongside the lessons. Install PostgreSQL locally, add an index and compare query plans with EXPLAIN; open two sessions and try different isolation levels.
• Draw the structures. Sketch a B-tree insert or a replication topology after each lesson.
• Use the case studies as practice. Attempt the schema and storage choice for each one before reading it.
• Plan about two weeks at an hour a day, including experiments.

What you will be able to do afterwards

Explain how a database stores and finds data, choose between relational and NoSQL stores based on access patterns, reason about isolation levels and replication lag, and describe how a distributed database elects a leader and recovers from failure.

Where it fits

It pairs naturally with System Design Fundamentals, which covers databases as one building block among many, and with Grokking the System Design Interview, where these choices come up in every design. Advanced System Design Interview, Volume II goes further with deep dives into Dynamo, Cassandra and BigTable.

Buying and access

The course is paid: you can buy it once for lifetime access, or get it as part of an all-access subscription covering more than 40 courses. Prices shown depend on your region and current offers, so check the course page. A free preview lets you read the opening lessons first, and a certificate is issued on completion.

Common questions

Do I need database experience? Basic SQL helps. The course starts from fundamentals and is marked beginner level.

Is it useful outside interviews? Yes. Indexing, isolation and replication are everyday concerns for backend engineers.

How long does it take? About 10 hours of reading, more with experiments.

Best for: engineers who want to understand database internals well enough to justify design decisions.