On Nov 27, 2012, at 5:53 AM, Daniel Rentsch wrote: > Hi all, > > We are trying to implement a locking mechanism which relies on the > incoming/used connections returned/used by SQLAlchemy. The problem we ran > into is that SQLAlchemy uses a new database connection after calling > expire_all() if we use the autocommit=True functionality. We expected that > only one connection is used in one session. > > More precisely: > > IF you use *autocommit=True* > IF you call call *expire_all* > AND AFTER THIS generate a query with more than one affected tables via > *filter_by* > THEN SQLAlchemy will use multiple connections
A Session using autocommit=True will pull a new connection from the connection pool for each individual execute operation, or each flush(). If you want only one connection used per session, you either need to stick with the recommended autocommit=False (the connection will be per-transaction, actually), or bind the Session to a single connection directly (sess = Session(bind=some_connection)). -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
