#32277: Aggregate of aggregate not allowed in window functions
-------------------------------------+-------------------------------------
Reporter: Héctor | Owner: nobody
Pablos |
Type: Bug | Status: new
Component: Database | Version: 3.0
layer (models, ORM) |
Severity: Normal | Keywords: window, aggregates
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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When trying do something like
{{{#!python
Sum(Count('field_name'))
}}}
Django raises a FieldError exception with the message {{{Cannot compute
Sum('count'): 'count' is an aggregate"}}}. That makes sense except when
{{{Sum(Count())}}} is the expression of a Window function, where nesting
two aggregates is a valid SQL expression:
{{{#!python
Window(expression=Sum(Count('field_name')), **omitted_window)
}}}
I may be missing some edge case here but would it be possible to check, in
the django.db.aggregates.Aggregate Func resolve_expression method, whether
the expression containing another aggregate is the main expression of a
Window function and, in that case, allow the execution of the SQL? Or is
there any way to circumvent this aggregation nesting limitation in window
functions?
--
Ticket URL: <https://code.djangoproject.com/ticket/32277>
Django <https://code.djangoproject.com/>
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