#6947: Auto increment field in sqlite
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Reporter: | Owner: nobody
ctrochalakis | Status: closed
Type: | Component: Database layer
Uncategorized | (models, ORM)
Milestone: | Severity: Normal
Version: SVN | Keywords: sqlite
Resolution: invalid | Has patch: 0
Triage Stage: | Needs tests: 0
Unreviewed | Easy pickings: 0
Needs documentation: 0 |
Patch needs improvement: 0 |
UI/UX: 0 |
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Changes (by django.bigfudge@…):
* ui_ux: => 0
* type: => Uncategorized
* severity: => Normal
* easy: => 0
Comment:
I'm not reopening this ticket myself, but I would like to petition for it
to be reopened because of a specific problem with django_reversion, and
likely other code intended to version django objects.
Quite reasonably, reversion versions are not deleted when an original
object is deleted. However, versions do use the deleted objects' id to
link back to that object. If using sqlite, when an object is deleted then
it's pk is freed up for reuse. When this happens, reversion_versions link
back to the wrong object, and in the admin it looks like there are more
versions than there actually are ( you get the full history for any object
which has had the pk in question).
Were Sebastian right that AUTOINCREMENT would only add new rows with
largest pk+1 then this would still be a problem: the object with the
largest PK could be deleted, and a new one would reuse this pk, and this
would still confuse reversion. However, quoting from the SQLITE docs:
"The behavior implemented by the AUTOINCREMENT keyword is subtly different
from the default behavior. With AUTOINCREMENT, rows with automatically
selected ROWIDs are guaranteed to have ROWIDs that have never been used
before by the same table in the same database."
http://www.sqlite.org/autoinc.html
So, if the AUTOINCREMENT keyword were added by django when creating tables
then this would prevent reversion getting confused. I'll cross post this
to the reversion people, but it seems to me that fixing django would be a
lot easier than trying to make the reversion app compatible with sqlite.
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Ticket URL: <https://code.djangoproject.com/ticket/6947#comment:3>
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