#32527: needs_rollback flag issue with implementation of backend that does not
support savepoint
-------------------------------------+-------------------------------------
Reporter: Hemant | Owner: nobody
Bhanawat |
Type: Bug | Status: new
Component: Database | Version: dev
layer (models, ORM) | Keywords: savepoint
Severity: Normal | needs_rollback database backend
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I am implementing a backend for Yugabyte. Yugabyte currently doesn't
support savepoints. Hence, in the backend, I have set uses_savepoints=
False
However, while running the test. I hit the following issue.
The error: "TransactionManagementError: An error occurred in the current
transaction. You can't execute queries until the end of the 'atomic'
block."
On some investigation, I found that this exception is thrown if
self.needs_rollback is True. The first test that uses savepoint passes
successfully. However, the second test has needs_rollback set as true and
hits this exception.
The problem stems from the following code of __enter__ function in
transaction.py
if self.savepoint and not connection.needs_rollback:
sid = connection.savepoint()
connection.savepoint_ids.append(sid)
else:
connection.savepoint_ids.append(None)
Basically, a None is inserted in the savepoint_ids when the savepoints are
not supported. And the following code in __exit__ function of
transaction.py, it sets needs_rollback as true:
if sid is None:
connection.needs_rollback = True
Can someone please clarify if this is an issue with the code or there is
something else that we can do at our layer. For the time being, we have
overridden the function savepoint of DatabaseWrapper to return 1. And, we
ask the users of our backend to not set savepoint=true in parameters of
transaction.atomic().
def savepoint(self):
return 1
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Ticket URL: <https://code.djangoproject.com/ticket/32527>
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