Database backends

migrant supports SQLite, PostgreSQL, and MySQL. Each is behind a cargo feature so you only build the drivers you need.

The library also has all to enable all three. No backend is enabled by default; invoking an operation whose feature is disabled returns Error::FeatureRequired rather than panicking. The pre-1.0 d-sqlite / d-postgres / d-mysql / d-all names remain as deprecated aliases.

SQLite

File-backed or in-memory. The sqlite CLI feature bundles SQLite; the library’s sqlite feature does not bundle it (enable rusqlite’s bundled feature in your own project if you want that). DDL is transactional, so migrations roll back cleanly on failure.

An in-memory database (:memory:) lives entirely in one connection. migrant keeps that connection alive for the life of the Config and its clones, so migrations and later queries see the same database. See Using migrant_lib.

PostgreSQL

DDL is transactional except for a handful of statements that cannot run in a transaction block (CREATE INDEX CONCURRENTLY, ALTER TYPE ... ADD VALUE, VACUUM, and similar). Opt those migrations out with the -- migrant:no-transaction directive; see Transactions.

TLS is chosen from the connection string’s sslmode:

• absent or sslmode=disable: no TLS (the default).
• any other value (prefer/require/verify-ca/verify-full): TLS using the system trust roots.
• ssl_cert_file in the config: verify the server against that root certificate.

The postgres driver needs libpq’s dev package (libpq-dev) to build.

MySQL / MariaDB

DDL commits implicitly, one statement at a time. A transaction cannot roll back DDL, so transaction wrapping only makes pure-DML migrations atomic. This is a property of the database; the -- migrant:no-transaction directive and no_transaction() do not change it. Plan MySQL DDL migrations so a partial application is safe to retry.

Static builds

The CLI’s vendored-openssl feature statically links OpenSSL for portable (musl) builds. Release binaries are built with all three database backends and the update feature (the musl target also enables vendored-openssl).