Database Tutorials in Build Your Own X: 14 Hands-On Projects from KV Stores to SQL Engines

The Build Your Own X repository hosts 14 curated database tutorials spanning key-value stores, B-Tree-based SQL engines, graph databases, and Redis-like servers across C, Go, Python, Rust, and five other languages.

The codecrafters-io/build-your-own-x repository is a curated collection of step-by-step tutorials for implementing technologies from scratch. For developers seeking to understand database internals, the repository's Database section provides database tutorials that cover everything from low-level disk storage to high-level query parsing.

Complete List of Database Tutorials

The database tutorials are located in the README.md file under the heading #### Build your own \Database`` (approximately lines 3939–3954). The section indexes 14 external tutorials organized by programming language:

C and C++

• C: Let's Build a Simple Database teaches you to build a basic disk-backed storage engine with a minimal query language (cstack.github.io/db_tutorial/).
• C++: Build Your Own Redis from Scratch guides you through creating an in-memory key-value store with networking, persistence, and pub/sub capabilities (build-your-own.org/redis).

C# and Clojure

• C#: Build Your Own Database demonstrates how to construct a simple relational engine with a custom query parser (codeproject.com).
• Clojure: An Archaeology-Inspired Database focuses on persistent immutable data structures for functional database design (aosabook.org).

Crystal and Go

• Crystal: Why you should build your own NoSQL Database builds a lightweight NoSQL store using Crystal (medium.com).

• Go: Three distinct tutorials are available:

  1. Build Your Own Database from Scratch: From B+Tree To SQL in 3000 Lines creates a full-stack B+Tree storage engine with SQL parser and query executor (build-your-own.org/database/).
  2. Code a database in 45 steps (TDD puzzles) uses test-driven development to construct a tiny DB with Go's testing package (trialofcode.org/database/).
  3. Build Your Own Redis from Scratch implements the networking layer, RESP protocol, and persistence for a Redis clone (www.build-redis-from-scratch.dev/).

JavaScript and Python

• JavaScript: Dagoba: an in-memory graph database provides a graph-oriented API for nodes and edges with query chaining (aosabook.org).

• Python: Two tutorials are featured:

  1. DBDB: Dog Bed Database implements a mini relational DB with a tiny SQL-like language (aosabook.org).
  2. Write your own miniature Redis with Python creates a simple key-value store exposing the Redis protocol (charlesleifer.com).

Ruby and Rust

• Ruby: Build your own fast, persistent KV store in Ruby constructs a persistent hash table on disk using Ruby's Marshal format (dineshgowda.com).
• Rust: The Build your own Redis client and server tutorial series uses async Tokio to implement RESP protocol handling and client libraries (tokio.rs).

Common Architecture Patterns

All database tutorials in the repository share a consistent high-level architecture comprising five core components:

1. Storage Layer — Implements either in-memory structures (hash maps, B-Trees) or on-disk file formats for data retention.
2. Query / Command Parser — Processes domain-specific languages or protocols such as SQL, RESP, or custom mini-languages.
3. Execution Engine — Translates parsed commands into storage layer operations including reads, writes, and range scans.
4. Networking Interface — For server-style tutorials, this component listens on sockets, decodes protocols, and manages client connections.
5. Persistence / Durability — Guarantees data survives restarts through write-ahead logs, snapshotting, or file appends.

Understanding these components clarifies why specific tutorials emphasize different aspects—the C tutorial focuses on low-level file I/O, while the Go B+Tree tutorial covers complete SQL engine implementation.

Code Implementation Examples

Minimal Key-Value Store in Python

This example illustrates the core storage pattern used in the Python Redis-style tutorials:

class MiniKV:
    def __init__(self):
        self.store = {}

    def set(self, key: str, value: str) -> str:
        self.store[key] = value
        return "OK"

    def get(self, key: str) -> str:
        return self.store.get(key, "(nil)")

# Usage

db = MiniKV()
print(db.set("name", "Codecrafters"))   # → OK

print(db.get("name"))                  # → Codecrafters

The linked tutorials expand this pattern with TCP listeners and RESP protocol handling.

B+Tree Node Structure in Go

The following snippet from the Build Your Own Database (B+Tree → SQL) tutorial demonstrates the low-level data structure powering the storage layer:

type BTreeNode struct {
    keys     []int           // sorted keys
    children []*BTreeNode    // nil for leaf nodes
    leaf     bool
}

// Insert a key into a leaf node (splitting handled by the caller)
func (n *BTreeNode) insertNonFull(k int) {
    i := len(n.keys) - 1
    if n.leaf {
        n.keys = append(n.keys, 0)               // grow slice
        for i >= 0 && k < n.keys[i] {
            n.keys[i+1] = n.keys[i]
            i--
        }
        n.keys[i+1] = k
    } else {
        // find child to descend into
        for i >= 0 && k < n.keys[i] {
            i--
        }
        i++
        if len(n.children[i].keys) == maxKeys {
            n.splitChild(i)
            if k > n.keys[i] {
                i++
            }
        }
        n.children[i].insertNonFull(k)
    }
}

This B+Tree implementation later supports a full SQL parser and query executor.

Locating the Database Tutorials in the Repository

The Build Your Own X repository functions as an index rather than hosting source code directly. To find the database tutorials:

• File Location: README.md in the repository root

• Section Header: Search for #### Build your own \Database``

• Line Range: Approximately lines 3939–3954 in the README

Each entry in this section links to external tutorials that provide complete source code and step-by-step instructions.

Summary

• The codecrafters-io/build-your-own-x repository indexes 14 database tutorials across 9 programming languages.
• Tutorial types range from in-memory key-value stores to B+Tree-backed SQL engines and graph databases.
• All tutorials follow a common architecture: storage layer, parser, execution engine, networking interface, and persistence mechanism.
• The tutorials are listed in README.md under the Database section (lines ~3939–3954).
• Code examples demonstrate core concepts including hash map storage (Python) and B+Tree node management (Go).

Frequently Asked Questions

What types of database engines are covered in the tutorials?

The tutorials cover key-value stores (Redis clones), relational databases (SQL engines with B+Tree storage), graph databases (in-memory node/edge systems), and NoSQL stores. Specific implementations include disk-backed storage engines, persistent hash tables, and mini SQL parsers.

Which programming languages have database tutorials available?

The repository lists database tutorials for C, C++, C#, Clojure, Crystal, Go (3 tutorials), JavaScript, Python (2 tutorials), Ruby, and Rust. This diversity allows you to learn database internals in your preferred language or compare implementations across different memory management models.

Are these database tutorials suitable for beginners?

While some tutorials like Let's Build a Simple Database (C) and DBDB (Python) are accessible to intermediate developers, others such as the B+Tree to SQL Go tutorial assume familiarity with data structures, file I/O, and concurrency. Most tutorials include progressive difficulty, starting with basic storage and advancing to networking and persistence.

Do the tutorials include networking and protocol implementation?

Yes. Several tutorials—particularly the Redis-from-scratch guides in C++, Go, Python, and Rust—include complete networking layer implementation. These cover socket programming, the RESP protocol, client-server architecture, and pub/sub messaging systems, providing full-stack database development experience.

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