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Level101 201 301 401

system design · 201

Intermediate

Master system design interviews with scalable architecture patterns, distributed systems, and real-world design challenges.

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Course curriculum

Authentication & Authorization 1

OAuth

OAuth Foundations & Core Concepts

Grant Types, PKCE, Access Tokens & Refresh Tokens

Advanced OAuth, OIDC, JWT Validation & Microservices

Interview Q&A (Staff/Principal)

Data Structures & Algorithms 6

Write-Ahead Log (WAL)

Foundations & Core Concepts

Internals — Log Records, Checkpoints & ARIES Recovery

System-Design Usage & Staff/Principal Interview

Bloom Filter

Foundations & Core Concepts

Internals — Bits, Hashes & the Math of Error

System-Design Usage & Staff/Principal Interview

Count-Min Sketch

Foundations & Core Concepts

Internals — The Grid, the Math & Tuning

System-Design Usage & Staff/Principal Interview

Consistent Hashing

Foundations & Core Concepts

Internals — Virtual Nodes, Replication & Bounded Load

System-Design Usage & Staff/Principal Interview

Quadtree

Foundations & Core Concepts

Internals & Implementation

System Design & Interview Mastery

Geohashing

Foundations & Core Concepts

Internals — Bit-Interleaving, the Z-Curve & the Boundary Problem

System-Design Usage & Staff/Principal Interview

Distributed Systems Primitives 6

Replication

Foundations & Core Concepts

Internals — Replication Logs, Lag Guarantees & Failover

System-Design Usage & Staff/Principal Interview

Partitioning (Sharding)

Foundations & Core Concepts

Internals — Rebalancing, Routing & Secondary Indexes

System-Design Usage & Staff/Principal Interview

Gossip Protocol

Foundations & Core Concepts

Internals — State, the Handshake & Failure Detection

System-Design Usage & Staff/Principal Interview

Paxos

Foundations & Core Concepts

Internals — The Protocol, Safety & Multi-Paxos

System-Design Usage & Staff/Principal Interview

Two-Phase Locking (2PL)

Foundations & Core Concepts

Internals — The Lock Manager, Deadlocks & Phantoms

System-Design Usage & Staff/Principal Interview

Distributed Transactions

Foundations & Core Concepts

Internals — 2PC, Sagas, TCC & the Outbox

System-Design Usage & Staff/Principal Interview

Databases & Data Modeling 11

SQL & Data Modeling

Foundations & Core Concepts

Internals — Indexes, Joins & the Query Planner

System-Design Usage & Staff/Principal Interview

SQL vs NoSQL

Foundations & Core Concepts

Internals — Storage Engines, Joins, Transactions & Scale

System-Design Usage & Staff/Principal Interview

Berkeley DB

Foundations & Core Concepts

Internals — Storage, WAL, Recovery & Replication

System Design & Staff/Principal Interview

RocksDB

Foundations & Core Concepts

Internals — Write Path, Read Path & Compaction

System-Design Usage & Staff/Principal Interview

Redis

Foundations & Core Concepts

Internals — The Single Thread & In-Memory Data Structures

Internals Advanced — Durability, Replication & Cluster

System-Design Usage & Staff/Principal Interview

Amazon DynamoDB

Foundations & Core Concepts

Internals — Partitions, Replication & The Write Path

Internals Advanced — Reads, Consistency, Capacity & Indexes

System-Design Usage & Staff/Principal Interview

Apache Cassandra

Foundations — The Masterless Ring

Internals — The Write Path & LSM Storage

Internals — Read Path, Consistency & Repair

System-Design Usage & Staff/Principal Interview

MongoDB

Foundations & Core Concepts

Internals — WiredTiger, the Write Path & Durability

Internals Advanced — Replication, Sharding & Tunable Consistency

System-Design Usage & Staff/Principal Interview

Neo4j (Graph Database)

Foundations & Core Concepts

Internals — Index-Free Adjacency & the Storage Engine

System-Design Usage & Staff/Principal Interview

Object Storage (S3 & Azure Blob)

Foundations & Core Concepts

Internals — Durability, Consistency & the Storage Engine

System Design & Staff/Principal Interview

Azure Synapse Analytics

Foundations & Core Concepts

Internals — MPP, Distributions & Columnstore

System Design & Staff/Principal Interview

Search 2

Apache Lucene

Foundations & Core Concepts

Internals — Segments, the FST & Scoring

System Design & Interview Mastery

Elasticsearch

Foundations & Core Concepts

Internals — The Inverted Index & Near-Real-Time Writes

Internals Advanced — Distribution, Routing & the Read Path

System-Design Usage & Staff/Principal Interview

Messaging & Streaming 7

Asynchronous Messaging

Foundations & Core Concepts

Internals — Brokers, Visibility Timeouts & Delivery Mechanics

System-Design Usage & Staff/Principal Interview

Publish–Subscribe Pattern

Foundations & Core Concepts

Internals — Brokers, Fan-out & Delivery Guarantees

System-Design Usage & Staff/Principal Interview

Webhooks

Foundations & Core Concepts

Internals — Reliable Delivery, Idempotency & Security

System-Design Usage & Staff/Principal Interview

Redis Pub/Sub

Foundations & Core Concepts

Internals — The Publish Path, Data Structures & Sharded Pub/Sub

System-Design Usage & Staff/Principal Interview

Apache Kafka

Foundations & Core Concepts

Internals — The Log, The Write Path & Consumers

Internals Advanced — Replication, EOS & KRaft

System-Design Usage & Staff/Principal Interview

Apache Flink

Foundations & Core Concepts

Internals & Exactly-Once

System Design & Interview Mastery

Apache Storm

Foundations & Core Concepts

Internals — Cluster Architecture, the Acker & Reliability

System-Design Usage & Staff/Principal Interview

Data Pipeline & Observability 3

Logstash

Foundations & Core Concepts

Internals — Pipeline Execution, Queues & Backpressure

System-Design Usage & Staff/Principal Interview

Scribe (Log Aggregation)

Foundations & Core Concepts

Internals — Stores, the Write Path & Store-and-Forward

System-Design Usage & Staff/Principal Interview

Scuba (Real-time Analytics)

Foundations & Core Concepts

Internals — In-Memory Storage, the Aggregation Tree & Sampling

System-Design Usage & Staff/Principal Interview

Architecture Patterns 3

CQRS

Foundations & Core Concepts

Internals — Command Path, Projections & Event Sourcing

System-Design Usage & Staff/Principal Interview

Circuit Breaker

Foundations & Core Concepts

Internals — State Machine, Rolling Windows & Probes

System-Design Usage & Staff/Principal Interview

Scheduler Agent Supervisor

Foundations & Core Concepts

Internals — State Machine, Leases & The Remediation Loop

System-Design Usage & Staff/Principal Interview

Scuba (Real-time Analytics)

maang.io System Design Series

Scuba is Facebook's in-memory database for real-time, ad-hoc analytics — the tool engineers reach for to debug a live incident. It holds recent data fully in RAM, sharded across many leaf servers, and answers arbitrary aggregations in sub-seconds via a scatter-gather tree, using sampling to bound cost. It trades exactness and history for speed and freshness — the opposite bargain from a warehouse.

This deep dive comes in three parts:

Foundations & Core Concepts — in-memory columnar storage and the fresh-vs-exact trade.
Internals — the scatter-gather aggregator tree, sampling, and sizing, with worked numbers.
Interview — Staff/Principal Q&A: real-time analytics design and sampling trade-offs.