Liquibase Extension: Session Lock Support

Provides session-level (vs. transaction-level) LockService implementations. Session-level locks get automatically released if the database connection drops, and overcome the shortcoming of the StandardLockService:

If Liquibase does not exit cleanly, the lock row may be left as locked. You can clear out the current lock by running liquibase releaseLocks which runs UPDATE DATABASECHANGELOGLOCK SET LOCKED=0.

Running liquibase releaseLocks in a micro-service production environment may not be really feasible.

Supported Databases

• MySQL
• MariaDB
• PostgreSQL
• Oracle

Support for other databases may be conveniently added by extending SessionLockService.

Oracle

The Oracle implementation relies on DBMS_LOCK. The user that executes liquibase must have EXECUTE privilege on DBMS_LOCK.

grant execute on SYS.DBMS_LOCK to <user>;  

Oracle does not provide a way to retrieve lock details (e.g. who owns a lock) without elevated privileges. You can use the following query to get lock details:

select locks_allocated.*, locks.*
from dba_locks locks, sys.dbms_lock_allocated locks_allocated
where locks.lock_id1 = locks_allocated.lockid
and locks_allocated.name = 'lockname';

However, it's possible to get some information about the current session from SYS_CONTEXT, so that's what gets returned by the DatabaseChangeLogLock object.

Usage

To use the new lockservice, simply add a dependency to the library. Because the priority is higher than the StandardLockService, it will automatically be used (provided the database is supported). The library supports Liquibase v3.x and v4.x.

Maven

<dependency>
    <groupId>com.github.blagerweij</groupId>
    <artifactId>liquibase-sessionlock</artifactId>
    <version>1.4.0</version>
</dependency>

Gradle

implementation 'com.github.blagerweij:liquibase-sessionlock:1.4.0'

Disclaimer

This module, both source code and documentation, is in the Public Domain, and comes with NO WARRANTY.

License

This module is using the Apache Software License, version 2.0. See http://www.apache.org/licenses/LICENSE-2.0.txt