Start Here — What Bytes & B-trees is and how to get the most out of it
If you just subscribed, this is the first thing to read. It takes 4 minutes and will save you from reading issues in the wrong order.
Welcome. This newsletter is a structured 3-year curriculum on how databases actually work — not how to use them, but how they’re built, why they make the decisions they make, and what happens inside the engine when your queries run.
Every issue goes deep on exactly one concept. Not a roundup. Not bullet points. One concept, from first principles, with working code, animated diagrams, and production context.
Here’s what you need to know to get the most out of it.
Who this is for
Engineers who use databases daily and want to understand what’s happening underneath. The sweet spot is senior backend engineers, architects, and SREs who can write complex queries but couldn’t confidently explain why a particular query plan was chosen, what MVCC is actually doing, or when to use SERIALIZABLE isolation.
If that’s you, you’re in the right place.
If you’re completely new to databases, start with Issue #001 and work forward. The curriculum is designed to be progressive — each issue builds on the ones before it.
Free vs paid
Free subscribers get the full core concept every issue — typically 1,200–2,000 words explaining the mechanism, one animated diagram, and a Query Lab puzzle. This is genuinely complete. You’ll understand the concept.
Paid subscribers ($15/month · $120/year) get the full article including:
Production failure modes — the specific ways the concept breaks in real systems
3–4 hands-on experiments with annotated output
A configuration checklist with verify and fix commands
Annotated Query Lab solution from the previous issue
Access to the private GitHub vault (see below)
The difference is the gap between knowing what something is and being able to use it safely in production.
The GitHub vault
Every paid issue ships a vault asset: a Python script, SQL file, or configuration guide that goes into a private GitHub repository. When you subscribe, you’re invited to the bytes-and-btrees-labs GitHub organisation and get access to everything in the vault — including all past assets, not just this week’s.
What’s currently in the vault:
Issue #007: WAL write sequence demo (Python, zero deps) + fsync benchmark script
Issue #008: Write cache verification script + 8-item durability checklist
Issue #009: All 4 isolation anomalies reproducible in one SQL file + SSI lock inspector
Issue #010: Query equivalence proofs + NULL trap demonstrations
Issue #011: 7-query NULL audit suite (find NULL bugs in your production schema)
Production checklists: index health check + isolation level audit + durability checklist
The vault grows by 3–4 assets every month.
Start with these five free issues
If you’re not sure where to begin, these five issues are the most referenced and the most shared:
Issue #001 — Data, storage & memory: first principles. Starts at the bottom of the stack and explains why disk access speed shapes every database design decision.
Issue #007 — Atomicity at the byte level. Traces a COMMIT from application to disk write by write. Explains what the WAL actually does and why ROLLBACK doesn’t need to touch disk.
Issue #008 — Durability: what fsync guarantees. The three ways your database’s durability claim can be silently false — and how to verify yours isn’t.
Issue #009 — Isolation levels visualised. All four anomalies, animated, with the exact SQL that reproduces each one and the isolation level that prevents it.
Issue #010 — SQL and relational algebra. Why the planner can safely rewrite your queries, and the algebraic reason NULL behaves the way it does.
The Query Lab
Every issue ends with a puzzle that requires applying the week’s concept to answer. The puzzle is free — post your answer in the comments. The annotated solution (with 2–3 valid approaches explained) is in the following issue’s paid section.
If you want to check your reasoning on past puzzles, the full solution archive is in the vault.
One thing that would help me
If you know exactly one engineer who would find this useful, forward them this issue. That’s genuinely the only growth mechanism this publication uses. No paid ads. No sponsor deals. Just word of mouth.
See you Sunday.
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