Documentation

Migrate and continuously sync MySQL and Postgres — including PlanetScale Neki, sharded Postgres — and import SQLite / Cloudflare D1. Correctness-first, loud failure by default.

sluice is an open-source tool for moving and keeping databases in sync between MySQL and Postgres, in all four directions. SQLite files (and a wrangler d1 export .sql dump), live Cloudflare D1 databases, CSV / TSV / NDJSON files, and mydumper / pscale dump directories also import into Postgres or MySQL, and SQLite is itself a migrate target — 14 engines are registered today (run sluice engines to list them). It is built around three surfaces you can use independently or end to end:

• Migrate — a one-shot schema + data copy, with deferred indexes/constraints for fast bulk load and per-table resume.
• Sync — change-data-capture streaming with a snapshot → CDC handoff and resumable checkpoints.
• Operate — run as a long-lived service behind /readyz and /metrics, or as one-shot jobs.

Start here #

• Getting started — install, connect, and run your first migration and sync.
• Command reference — every command, its key flags, and worked examples.
• Configuration — connection strings, environment variables, the YAML config file, and global flags.

PlanetScale Neki — sharded Postgres #

Neki is PlanetScale’s horizontally-sharded PostgreSQL, and sluice reaches it with the ordinary postgres driver — there is no neki engine, no --target-driver neki, and nothing to configure. sluice detects it from the server’s own version() and adapts the handful of behaviours that differ.

Measured against live clusters, not inferred: migrate and sync into it including into an already-sharded database, across a live reshard with no loss or duplication, and through a MoveTables cutover — where the stream halts loudly with its position intact rather than drifting. Migrate out of it works too, including from a sharded database. Continuous sync out of Neki does not: the router refuses a replication connection outright, measured even on an unsharded database.

Sharding changes what your schema guarantees, and sluice refuses the shapes that would silently corrupt rather than letting them through — a UNIQUE constraint is only unique within a shard, and an upsert whose conflict key does not contain the shard key inserts a duplicate instead of updating. Migrate PlanetScale Postgres to Neki is the tested step-by-step procedure, and supported directions has the full matrix.