#23061: Oracle SQL compiler adding outer pagination selects causing ORA-00907:
missing right parenthesis when used with select_for_update.
-------------------------------------+-------------------------------------
Reporter: michael.miller@… | Owner: shai
Type: Bug | Status: assigned
Component: Database layer | Version: 1.7-rc-1
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Ready for
Keywords: oracle sql compiler | checkin
ORA-00907 | Needs documentation: 0
Has patch: 1 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by shai):
Replying to [comment:11 apollo13]:
> Can't we just revert the fix for #6785?
I'd like to have better reasons for reverting it than "Oracle is retarded
and the Django backend hasn't managed to work around that."
Replying to [comment:12 michael.miller@…]:
> I'm not excited by all my gets now being wrapped in two additional
selects. Our DBAs probably won't be either. Is it possible to create a db
back end flag for slicing get results and have it turned off on Oracle.
I think it is better to do this, not via flags, but rather by providing a
hook for the backend. That way, the Oracle backend (and also others) could
implement #6785 by special fetches instead of slicing the query.
The kind of hook I have in mind is: Replace the line in `QuerySet.get()`
which slices the query with code which gets a compiler and calls a new
method on it, `compiler.prepare_for_get(query)`. The default
implementation of `prepare_for_get()` will slice the query, but the Oracle
one will just mark it as a `get`. Then, the backend, when executing the
query and fetching its results, will know to fetch only up to 21 rows (how
exactly this part works is still not clear to me, because at that point
the backend only gets sql, but we'll figure it out).
My capacity for working on any of this until the end of next week is quite
limited, as I am on a family vacation.
> If not the patch should work
All of the proposed solutions so far still leave the original deep problem
unsolved: Sliced for-update queries do not work on Oracle. However, this
has probably been the case for a very long time, and I don't see it
reported, so apparently that should not be a release blocker. Thanks for
validating that the smaller issue of `get()` is indeed the only problem
for you.
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Ticket URL: <https://code.djangoproject.com/ticket/23061#comment:13>
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