Labs

Reading about a storage engine and building one are different activities. These are the second kind. Your code runs in a sandboxed worker in this tab — nothing is uploaded.

5 labsJavaScriptno setup

01 · Foundations

Module

coreBuild the Latency Report30 min

Turn a pile of raw response times into the summary an on-call engineer can act on — and the SLO verdict that follows from it.

02 · Data Models

Module

coreTraverse a Property Graph40 min

Answer the questions a relational schema struggles with — reachability at unknown depth, shortest paths, and overlapping tenures — by walking edges yourself.

03 · Storage

Module

coreBuild a Log-Structured Store45 min

The two-line database, done properly — append-only log, in-memory index, tombstones, and compaction that never mutates what it has already written.

coreSparse Lookup and the k-Way Merge50 min

Sorting bought a sparse index and a streaming merge. Write both, including the tombstone rule that stops deleted records rising from the dead.

04 · Encoding

Module

stretchWrite a Tagged Binary Encoder1 hr

Build the format from lesson 3 — varints, tags, length prefixes — then use it to reproduce the silent data-loss bug and fix it.