sqlalchemy, postgresql and relationship stuck in “idle in transaction”

Question

I have a problem related to sqlalchemy and postgresql.

class Profile(Base):
  ...

  roles = relationship(\'Role\', secondary=role_profiles,
                             


        

Answer 1

Starting with SQLAlchemy 0.8.2 you can disable the implicit BEGIN statements when calling create_engine()

engine = create_engine(uri, isolation_level="AUTOCOMMIT")

There are some subtle implications to this change. First, there statements that were not quietly hid in unterminated transaction will be quietly ignored

session.execute("DELETE FROM department WHERE department_id=18")
sys.exit(0)

default:

LOG:  statement: BEGIN
LOG:  statement: show standard_conforming_strings
LOG:  statement: DELETE FROM department WHERE department_id=18
LOG:  unexpected EOF on client connection with an open transaction

autocommit:

LOG:  statement: show standard_conforming_strings
LOG:  statement: DELETE FROM department WHERE department_id=18

Second, updating multiple updates are no longer automic, and rollback() is only conditionally effective:

department = Department(u"HR")
session.add(department)
session.flush()
employee = Employee(department.department_id, u'Bob')
session.add(employee)
session.rollback()

default:

LOG:  statement: BEGIN
LOG:  statement: INSERT INTO department (name) VALUES ('HR') RETURNING department.department_id
LOG:  statement: ROLLBACK

autocommit:

LOG:  statement: INSERT INTO department (name) VALUES ('HR') RETURNING department.department_id

Setting SQLAlchemy's isolation_level on the Engine object is effective for many applications. It unfortunate that Session.begin() does not always mean BEGIN TRANSACTION;