SQLAlchemy 0.7 Documentation
The Glossary is a brand new addition to the documentation. While sparse at the moment we hope to fill it up with plenty of new terms soon!
This term refers to when an operation terminates some state which corresponds to a service of some kind. Specifically within SQLAlchemy, it usually refers to a reference to a database connection, and typically a transaction associated with that connection. When we say “the operation releases transactional resources”, it means basically that we have a Connection object and we are calling the Connection.close() method, which has the effect of the underlying DBAPI connection being returned to the connection pool. The connection pool, when it receives a connection for return, unconditionally calls the rollback() method of the DBAPI connection, so that any locks or data snapshots within that connection are removed. Then, the connection is either stored locally in memory, still connected but not in a transaction, for subsequent reuse by another operation, or it is closed immediately, depending on the configuration and current state of the connection pool.