High Level Design 101
Designing systems that scale — load balancing, caching, replication, NoSQL internals, and real case studies.
How big websites stay fast for millions of people
⏱ 39 min read · 📖 7 topics
Welcome to your very first High-Level Design class.
How big systems spread the work — fairly and without chaos
⏱ 45 min read · 📖 9 topics
In Session 1 we learned that real systems run on many servers, not one.
Caching: how systems remember answers so they don't redo work
⏱ 34 min read · 📖 5 topics
Welcome to your first caching class.
Caching, Part 2: how caches decide what to forget — and stay correct
⏱ 43 min read · 📖 4 topics
In Session 3 we learned what a cache is and why it makes systems fast.
Putting caching to work on real systems
⏱ 39 min read · 📖 6 topics
In Sessions 3 and 4 we built up the theory of caching — what to keep, when to throw it away, and how to keep it honest.
From one big app to many small services — and a chat app you could ship
⏱ 21 min read · 📖 5 topics
So far we've designed pieces of systems.
The Storage Layer — CAP, PACELC & Replication
⏱ 39 min read · 📖 8 topics
So far our system has been mostly one box doing the thinking.
One writer, many readers — and how strict we want to be about it
⏱ 34 min read · 📖 6 topics
Last session we met the CAP theorem and the idea that data gets copied across machines.
When to trust a relational database — and when to walk away
⏱ 40 min read · 📖 6 topics
Up to now we've treated "the database" as one trusty box.
How write-heavy databases store data: LSM Trees
⏱ 35 min read · 📖 6 topics
Ever wondered how databases that swallow millions of writes per second — Cassandra, RocksDB, the engine behind your favourite chat app — actually…
How LSM-tree databases read data fast
⏱ 37 min read · 📖 5 topics
Last session we learned how LSM-tree databases write data blazingly fast by only ever appending.
How Google finishes your search before you do
⏱ 34 min read · 📖 8 topics
You start typing "how to ti…" and a list pops up — "how to tie a tie," "how to tie shoes" — before you've finished the word.
Typeahead-2: actually building, storing, and scaling autocomplete
⏱ 27 min read · 📖 8 topics
In the previous session we sketched what a search "type-as-you-go" suggestion box should do.
How chat apps and Netflix actually work
⏱ 40 min read · 📖 12 topics
Today we stop learning building blocks one at a time and instead build two real systems : a messaging app like WhatsApp, and a video platform like…
Picking the right NoSQL database — and using it for chat
⏱ 36 min read · 📖 6 topics
"NoSQL" isn't one thing — it's a family of four very different database styles, each good at a different job.
Designing IRCTC: the whole course, in one system
⏱ 23 min read · 📖 4 topics
This is the grand finale.