#24096: GROUP BY on oracle fails with TextField and BinaryField
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Reporter: jarshwah | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
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 jarshwah):
Yes, this is the general case of #20971, so it is almost a duplicate. IMO
the linked ticket is a bit confusing. Not sure if we should close this as
a duplicate and add this information to the other or not.
In any case, Oracle does not support grouping by primary key. All fields
listed in the select list must also be present in the group by list.
There are a few options I can think of:
1. Document the limitation (must use values()) on Oracle
2. Remove LOB type columns from the select and group by list
3. Convert (with lossy behaviour) the LOBs to reasonable types in both
lists
4. Remove deferred columns from GROUP BY when the PK is available
5. A combo of 2 and 4 - automatically defer LOB type columns and remove
them from GROUP BY
Option 5 provides the most reasonable behaviour here I think, as it
shouldn't change results, and won't be lossy with regards to data. It
should also allow the same django code to run on all backends, at the
expense of an extra query on Oracle to fetch LOB results on demand.
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Ticket URL: <https://code.djangoproject.com/ticket/24096#comment:3>
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