Notes from beneath the surface

Learn how it works inside. By playing it.

Short interactive puzzles about the tools you use every day. Pick a track.

3 puzzles · playable

Inside PostgreSQL

  • 1. The heap page
  • 2. Index or sequential scan?
  • 3. The booking race
Not played yetPlay →
3 puzzles · coming soon

Inside Ruby

  • 1. Garbage collection
  • 2. Method lookup
  • 3. Threads and the GVL
PreviewOpen →
By Adarsh Mishra. Your progress stays in this browser.
← All tracks
Notes from beneath the surface

Three puzzles from inside PostgreSQL

Play with each puzzle, then answer its questions. Get them right to unlock the next one.

Points 0 Question 0 of 0 Best 0
    By Adarsh Mishra. Simplified models for learning, not exact PostgreSQL internals.
    ← All tracks
    Track · Inside Ruby

    Inside Ruby is being built

    Same format as the Postgres track: play a small scene, then answer questions to unlock the next puzzle.

    1. 1
      Garbage collectionDrop references between objects, run GC, and see what gets swept.
    2. 2
      Method lookupToggle include, prepend and extend, then guess which method runs first.
    3. 3
      Threads and the GVLTwo threads, one counter. Add a Mutex and watch lost updates disappear.
    Want to know when it opens?
    Subscribers get new tracks and bonus puzzles first.
    Subscribe to the newsletter Play the PostgreSQL track meanwhile