Can a prompt replace PlanetScale?

Build a workflow for running MySQL schema migrations without locking tables, using gh-ost, an existing, mature open-source tool originally built at GitHub for exactly this, rather than attempting to reimplement online schema change, which is genuinely hard distributed-systems work. Set up a self-hosted MySQL instance (Docker Compose is fine for personal use). Install gh-ost and write a small wrapper script that takes a migration SQL statement, runs it through gh-ost's triggerless copy-and-swap approach (it copies the table's data in the background, tracks changes with binlog streaming, then does a fast atomic swap), and reports progress. Track applied migrations in a metadata table so you know what's been run. Add a dry-run mode, which gh-ost supports natively, so a migration can be validated before actually running. Do not attempt to build Vitess-style horizontal sharding, a deploy-request review workflow, or managed automatic backups — those are out of scope; this wraps gh-ost for one database, not PlanetScale's actual multi-tenant infrastructure. Requires hosting for the MySQL instance; no other external service needed, since gh-ost itself is free and open source.