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For self-directed learners

Turn any material into a course built for you.

Books, papers, lecture notes, slides. Bring what you are learning from and the time you have. An agent reads all of it properly, top to bottom, and builds the syllabus, the readings, the exercises, and a knowledge graph you keep.

Create your first course See how it works

Free to start. Studying is never metered.

Storage engines and replication
Week 3 of 9 · Module 3: Replication
on pace
  1. Quorum reads and write conflicts
    3 concepts due
    6 min
  2. Leaders and followers
    DDIA ch. 5, pp. 152–161
    18 min
  3. When does a leaderless quorum return stale data?
    Multiple choice · 2 of 4
    12 min
  4. Module 3 check
    Free text, graded against your materials
    4 min
40 min · budget 45 minStart with reviews
You buy a serious book. You read three chapters. Four months later you can recall the phrase “quorum reads” and nothing operational about them.

Serious books are written as courses. Nobody teaches them to you. There is no syllabus, no problem set, no checkpoint, no record.

What’s missing is not a summary. It’s course construction.

How it works

Three steps. The second one is the hard part, and it is the part we do for you.

  1. 01

    Bring your materials

    Upload the PDFs, as many as you like. Write the goal in your own words, say how many hours a week you have, and pick the exercise formats you want.

  2. 02

    The agent reads all of it properly

    Outline, search, define, follow every cross-reference. The way a coding agent reads a repository, not a summary of each chapter. Every section of every source gets a decision you can audit.

  3. 03

    Study it, every day

    A session sized to your budget: readings by page, exercises graded against your materials, reviews scheduled before you forget. The graph of what you know grows.

Coverage ledger

every section, one decision
3 covered1 summarized1 skipped0 out of scope
  • 3.3 Column-Oriented Storage
    Analytics workloads are out of scope for the goal you wrote.
    Skipped
  • 5.1 Leaders and Followers
    Covered
  • 5.2 Problems with Replication Lag
    Covered
  • 5.3 Multi-Leader Replication
    Your goal is single-region design reviews; kept as one reading.
    Summarized
  • 5.4 Leaderless Replication
    Covered

Reading depth

logged on every build
Coverage sections with a disposition
100%
Read ratio of the books actually read
0.71
Grounding source spans per concept, median
3.4
Traversal outline depth of spans read
3.8
Cross-refs book references resolved
82%

Five numbers, logged on every build, so depth is measured rather than claimed. Grounding is the honest one: a shallow generator cites one chunk per concept; a deep one cites the definition, the example, and the warning.

What you get

A well-designed course. Deep questions, with answers grounded in your materials.

You learn by repetition and by a feedback loop that shows you getting better. Every screen below exists to keep that loop going.

Module 3 · Week 3active

Replication

  • Explain why replication lag produces the three consistency anomalies, and name each.
  • Choose between leader-based and leaderless replication for a stated failure model.
Readings
  • DDIA ch. 5 · pp. 152–16118 min
  • DDIA ch. 5 · pp. 161–16714 min
6 concepts · 9 exercises · 3 h 10 min
Exercise · multiple choice

When does a leaderless quorum return stale data?

  1. aWhenever fewer than n nodes acknowledged the write
  2. bWhen w + r ≤ n, so the read and write sets can miss each other
  3. cOnly during a leader failover

Grounded in DDIA pp. 179–181. A wrong answer sends you to the page, not to a summary.

Knowledge graphLearning

Quorum

The minimum number of nodes that must confirm a read or write for the two to be guaranteed to overlap.

Source spans
  • Definitionp. 179
  • Worked examplep. 181
  • Where the book warns youp. 183
NeedsReplication lagLeaderless replication
Progresson pace

Projected finish: 14 November

  1. Week 1
  2. Week 2
  3. Week 3
  4. Week 4
  5. Week 5
  6. Week 6
  7. Week 7
  8. Week 8
  9. Week 9
Solid
14
Learning
7
Due today
3

Not a summary. Not a chatbot over your PDF.

Coverage you can audit

Every leaf section is covered, summarized, or skipped with a reason. No silent omissions, ever.

Exercises in your formats

Multiple choice, free text, code, formulas, flashcards. Graded against your materials, with the page one click away.

A graph you keep

Concepts, prerequisites, source spans, and your state on each. It outlives the course and connects to the next one.

Start with the material you most want to actually finish.

Create an account, upload your materials, write down what you want to be able to do. The course is built while you go about your day.

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