#13906: REPEATABLE READ (as used by default on MySQL) breaks atleast
QuerySet.get_or_create().
-------------------------------------+-------------------------------------
Reporter: | Owner:
sebastian_noack | Status: new
Type: | Component: Database layer
Cleanup/optimization | (models, ORM)
Milestone: 1.4 | Severity: Normal
Version: SVN | Keywords: mysql transaction
Resolution: | isolation
Triage Stage: Accepted | Has patch: 1
Needs documentation: 1 | Needs tests: 0
Patch needs improvement: 1 | Easy pickings: 0
UI/UX: 0 |
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Comment (by mila):
I would use [http://dev.mysql.com/doc/refman/5.0/en/innodb-locking-
reads.html SELECT ... FOR UPDATE or SELECT ... LOCK IN SHARE MODE] option
and get fresh data instead of changing global transaction level because of
one concrete bug.
This should be easy now when Queryset.select_for_update method was
implemented [16058].
Note that "REPEATABLE READ" isolation level is
[http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt more strict]
that "READ COMMITTED" - which means that switching to "READ COMMITTED"
level does not guarantee anything extra. If it fixes this problem it is
just implementation detail which we should not rely on.
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Ticket URL: <https://code.djangoproject.com/ticket/13906#comment:20>
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