Hello, I have a question about when "close" should or should not be called on a session.
At http://docs.sqlalchemy.org/en/latest/orm/session_transaction.html it says: "When the transactional state is completed after a rollback or commit, the Session releases all Transaction and Connection resources, and goes back to the “begin” state, which will again invoke new Connection and Transaction objects as new requests to emit SQL statements are received." >From this description, given that the session releases its resources, it seems that there's no need to call "close" explicitly on the session, whether or not you want to re-use the session object or not. There is also some example code, which doesn't invoke session.close(). session = Session()try: ... # commit. The pending changes above # are flushed via flush(), the Transaction # is committed, the Connection object closed # and discarded, the underlying DBAPI connection # returned to the connection pool. session.commit()except: # on rollback, the same closure of state # as that of commit proceeds. session.rollback() raise However, under http://docs.sqlalchemy.org/en/latest/orm/session_basics.html#when-do-i-construct-a-session-when-do-i-commit-it-and-when-do-i-close-it there's a different example, this time explicitly calling close() on the session: def run_my_program(): session = Session() try: ThingOne().go(session) ThingTwo().go(session) session.commit() except: session.rollback() raise finally: session.close() So my question is, what does session.close() do that commit/rollback does not? It's also not entirely clear to me if a session object can be reused after it has been closed. At http://docs.sqlalchemy.org/en/latest/orm/session_api.html#sqlalchemy.orm.session.Session.close it says: "If this session were created with autocommit=False, a new transaction is immediately begun. Note that this new transaction does not use any connection resources until they are first needed." So it sounds to me like a closed session *can* be re-used. Is that correct? Related to this is calling scoped_session.remove. At http://docs.sqlalchemy.org/en/latest/orm/contextual.html#unitofwork-contextual it says: web request ends -> # the registry is instructed to # remove the Session Session.remove() As I understand it, this calls "close" on the underlying session *and* removes it from the registry, so you get a fresh Session next time. However if the framework already does a commit/rollback, why not just allow the registry to retain the same session object? Thanks, Brian. -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
