Building Scylla: lessons on compatibility

SQLite is embedded everywhere - phones, browsers, IoT devices. It's reliable, battle-tested, and feature-rich. But what if you want concurrent writes? Or CDC for streaming changes? Or vector indexes for AI workloads? The SQLite codebase isn't accepting new contributors, and the test suite that makes it so reliable is proprietary. So how do you evolve an embedded database that's effectively frozen?

Glauber Costa spent a decade contributing to the Linux kernel at Red Hat, then helped build Scylla, a high-performance rewrite of Cassandra. Now he's applying those lessons to SQLite. After initially forking SQLite (which produced a working business but failed to attract contributors), his team is taking the bolder path: a complete rewrite in Rust called Turso. The project already has features SQLite lacks - vector search, CDC, browser-native async operation - and is using deterministic simulation testing (inspired by TigerBeetle) to match SQLite's legendary reliability without access to its test suite.

The conversation covers why rewrites attract contributors where forks don't, how the Linux kernel maintains quality with thousands of contributors, why Pekka's "pet project" jumped from 32 to 64 contributors in a month, and what it takes to build concurrent writes into an embedded database from scratch.

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Turso: https://turso.tech/

Turso GitHub: https://github.com/tursodatabase/turso

libSQL (SQLite fork): https://github.com/tursodatabase/libsql

SQLite: https://www.sqlite.org/

Rust: https://rust-lang.org/

ScyllaDB (Cassandra rewrite): https://www.scylladb.com/

Apache Cassandra: https://cassandra.apache.org/

DuckDB (analytical embedded database): https://duckdb.org/

MotherDuck (DuckDB cloud): https://motherduck.com/

dqlite (Canonical distributed SQLite): https://canonical.com/dqlite

TigerBeetle (deterministic simulation testing): https://tigerbeetle.com/

Redpanda (Kafka alternative): https://www.redpanda.com/

Linux Kernel: https://kernel.org/

Datadog: https://www.datadoghq.com/

Glauber Costa on X: https://x.com/glcst

Glauber Costa on GitHub: https://github.com/glommer

Kris on Bluesky: https://bsky.app/profile/krisajenkins.bsky.social

Kris on Mastodon: http://mastodon.social/@krisajenkins

Kris on LinkedIn: https://www.linkedin.com/in/krisjenkins/

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0:00 Intro

3:16 Ten Years Contributing to the Linux Kernel

15:17 From Linux to Startups: OSv and Scylla

26:23 Lessons from Scylla: The Power of Ecosystem Compatibility

33:00 Why SQLite Needs More

37:41 Open Source But Not Open Contribution

48:04 Why a Rewrite Attracted Contributors When a Fork Didn't

57:22 How Deterministic Simulation Testing Works

1:06:17 70% of SQLite in Six Months

1:12:12 Features Beyond SQLite: Vector Search, CDC, and Browser Support

1:19:15 The Challenge of Adding Concurrent Writes

1:25:05 Building a Self-Sustaining Open Source Community

1:30:09 Where Does Turso Fit Against DuckDB?

1:41:00 Could Turso Compete with Postgres?

1:46:21 How Do You Avoid a Toxic Community Culture?

1:50:32 Outro