Take a one line product request to a design you can defend, in forty minutes, where every component in the drawing was forced by a number you estimated out loud rather than named from memory

A System Design in Forty Minutes

The forty minute path from a vague request to a defended design, where every box on the board is there because an estimate put it there.

8 lessons, written and corrected before you arrived. Reading them here needs no account. The first reads the whole way through; the others open and then stop, because a page nobody owns cannot tell who is reading it. Starting the course gives you your own copy, where every idea has problems standing under it and you can ask about any sentence.

Start reading

01What a One Line Design Request Actually Asks ForA one line request becomes designable once you have written the one job, the two or three operations with their input and output shapes, and the things you are leaving out.
02Estimating the Load Before You Draw Anythingopening onlyWhere every figure a design quotes comes from, derived out loud to one significant figure from how many people do what how often, with the arithmetic shown.
03The One Machine Version, and the Number at Which It Breaksopening onlyDesign a link shortener on a single machine, then compute exactly which of its three ceilings the demand breaks and by what factor, so every later component has something it repairs.
04Where 360,000 Reads a Second Actually Goopening onlyDerive the cache hit rate that brings a peak read load inside what the store can serve, the memory that hit rate costs, and the number of copies needed the moment the cache is empty.
05Splitting the Writes, and the Number That Decides How Many Piecesopening onlyWhy the shard count for a link shortener comes from the stored bytes rather than the write rate, how the key gets chosen, and what a popular key and a cross shard question each cost to repair.
06What a Reader Sees While Something Is Brokenopening onlyA failure exposes a promise, so the promise is priced here in round trips, in machines and in the records a lagging copy cannot serve, once for the link row and once for the click counter.
07Justifying Every Box in the Drawing With the Number That Forced Itopening onlyHow to draw a final design in which every component can be defended by the estimate that forced it, which boxes to leave out, and what to change first when one estimate moves.
08Where Each of the Forty Minutes Goes, and the Two Mistakes That Cost Tenopening onlyThe forty minutes divided into seven stages with the number that has to leave each one, the two mistakes that cost the most minutes, and a second brief run end to end at that pace.