# Locking

Explicit table-level locks are supported through the `psqlextra.locking.postgres_lock_model()` and `psqlextra.locking.postgres_lock_table()` methods. All table-level lock methods are supported.

Locks are always bound to the current transaction and are released when the transaction is committed or rolled back. There is no support (in PostgreSQL) for explicitly releasing a lock.

Warning

Locks are only released when the outer transaction commits or when a nested transaction is rolled back. You can ensure that the transaction you created is the outermost one by passing the `durable=True` argument to `transaction.atomic`.

Note

Use django-pglocks if you need a advisory lock.

## Locking a model

Use `psqlextra.locking.PostgresTableLockMode` to indicate the type of lock to acquire.

    from django.db import transaction

    from psqlextra.locking import PostgresTableLockMode, postgres_lock_table

    with transaction.atomic(durable=True):
        postgres_lock_model(MyModel, PostgresTableLockMode.EXCLUSIVE)

    # locks are released here, when the transaction committed

## Locking a table

Use `psqlextra.locking.postgres_lock_table()` to lock arbitrary tables in arbitrary schemas.

    from django.db import transaction

    from psqlextra.locking import PostgresTableLockMode, postgres_lock_table

    with transaction.atomic(durable=True):
        postgres_lock_table("mytable", PostgresTableLockMode.EXCLUSIVE)
        postgres_lock_table(
            "tableinotherschema",
            PostgresTableLockMode.EXCLUSIVE,
            schema_name="myschema"
        )

    # locks are released here, when the transaction committed