Drivers

Queen supports several databases, but the production contract is intentionally PostgreSQL-first.

Start with Support Matrix when comparing driver guarantees. Current limitations to keep in mind:

• SQLite locking is for local/single-process use, not distributed coordination.
• ClickHouse locking is best-effort; keep deployment migrators serialized.
• CockroachDB retries 40001 serialization errors up to three times; Go callbacks must be retry-safe.
• MySQL and ClickHouse record migration metadata separately from the body.

The detailed edge list lives in Known Limitations.

Database	Driver package	Locking	Transaction behavior	Migration record atomic with body
PostgreSQL	drivers/postgres	Production-ready advisory lock pinned to one connection	Yes by default; opt-in non-transactional commands	Yes by default; recovery markers for non-transactional commands
MySQL	drivers/mysql	GET_LOCK based	Depends on MySQL DDL semantics	No
SQLite	drivers/sqlite	Local/single-process use recommended	Yes for transactional statements	Yes
ClickHouse	drivers/clickhouse	Best-effort table guard	No true transaction support	No
CockroachDB	drivers/cockroachdb	Table row with expiry	Serializable transactions with bounded retries	Yes
MSSQL	drivers/mssql	Application lock	Yes for transactional statements	Yes

PostgreSQL

Use PostgreSQL when you need the strongest Queen behavior today:

• advisory lock pinned to one connection;
• SQL and Go-function migration body inside a transaction;
• migration record written in the same transaction as the migration body;
• pgxpool adapter support.

q := queen.New(postgres.New(db))

Detailed page: PostgreSQL Driver.

MySQL

MySQL uses GET_LOCK on a pinned connection and normal database/sql transaction execution. DDL rollback behavior follows MySQL rules.

Detailed page: MySQL Driver.

SQLite

SQLite is useful for tests, local tools, and single-process applications. Do not treat the current SQLite lock path as distributed coordination between multiple migrator processes.

Detailed page: SQLite Driver.

ClickHouse

ClickHouse does not provide the same transaction model as PostgreSQL. Treat its migration lock as a best-effort guard and keep migrations operationally serialized.

Detailed page: ClickHouse Driver.

CockroachDB

CockroachDB retries 40001 serialization failures up to three times. Go-function callbacks can run more than once and must be retry-safe; an error after the retry limit still needs operator review.

Detailed page: CockroachDB Driver.

MS SQL Server

MSSQL uses sp_getapplock / sp_releaseapplock on a pinned session connection.

Detailed page: MS SQL Server Driver.