#20971: Annotating a count of distinct ForeignKey (a) of a reverse foreignkey
(b)
doesn't work on oracle if (a) has any TextFields
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Reporter: kimvais@… | Owner: nobody
Type: Uncategorized | Status: new
Component: Database layer (models, ORM) | Version: 1.5
Severity: Normal | Keywords: oracle
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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If there is a model X that has foreignkey to model Y and X has foreign key
to Z and has TextFields the query for an instance of Y fails.
E.g.
y.xys.all().defer(list_of_all_text_fields).annotate(Count('z__pk',
distinct=True) causes "DatabaseError: ORA-00932: inconsistent datatypes:
expected - got NCLOB"
This is probably(?) because the "GROUP BY" clause will contain all the
deferred fields.
As a workaround I have to do sum(len(set(x)) for x in
y.xys.all().values_list('z__pk'))
Works flawlessly on PostgreSQL.
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Ticket URL: <https://code.djangoproject.com/ticket/20971>
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