#29760: Cursors are being closed explicitly in autocommit mode
-------------------------------------+-------------------------------------
Reporter: Ali Teoman Unay | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.11
(models, ORM) |
Severity: Normal | Resolution:
Keywords: cursor, sql, | Triage Stage:
database, autocommit, | Unreviewed
transactions, postrgresql, |
psycopg |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Ali Teoman Unay):
Replying to [comment:5 Tim Graham]:
> Can you give steps to reproduce the error?
>
> I read the psycopg2 docs that you linked to but I didn't spot the place
where it says "server-side cursors should not be closed explicitly if it
is in autocommit mode."
"Named cursors are usually created WITHOUT HOLD, meaning they live only as
long as the current transaction. Trying to fetch from a named cursor after
a commit() or to create a named cursor when the connection is in
autocommit mode will result in an exception. It is possible to create a
WITH HOLD cursor by specifying a True value for the withhold parameter to
cursor() or by setting the withhold attribute to True before calling
execute() on the cursor. It is extremely important to always close() such
cursors, otherwise they will continue to hold server-side resources until
the connection will be eventually closed. Also note that while WITH HOLD
cursors lifetime extends well after commit(), calling rollback() will
automatically close the cursor."
from [http://initd.org/psycopg/docs/usage.html#server-side-cursors here]
It is hard to reproduce the error since it appears each time in a
different line of our code and it is very rare. I believe it appears when
the cursor is destroyed before the transaction ended and it points to a
synchronization error which might be related to this issue.
--
Ticket URL: <https://code.djangoproject.com/ticket/29760#comment:6>
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