#16554: Unnecessary join when using a reverse foreign-key relationship in
separate
filter or aggregate calls
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
bendavis78 | Status: closed
Type: Bug | Component: Database layer
Milestone: | (models, ORM)
Version: SVN | Severity: Normal
Resolution: invalid | Keywords:
Triage Stage: | Has patch: 0
Unreviewed | Needs tests: 0
Needs documentation: 0 | Easy pickings: 0
Patch needs improvement: 0 |
UI/UX: 0 |
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Comment (by akaariai):
If I am not mistaken, the aggregate example is valid - it produces wrong
results. Author having two different SCIFI books will have pages
calculated twice.
But the chained filters is not valid, as one query is asking for a model
which has a book with genre of SCIFI and more than 500 pages, the other is
asking for a model which has a book with genre of SCIFI and a book which
has more than 500 pages. So, in the first example there must be one
matching book, in the second example the books matching the condition can
be different ones.
I am leaving this as closed, as I don't know what to do for a half-valid
ticket and I haven't actually verified that the aggregate example produces
wrong results.
--
Ticket URL: <https://code.djangoproject.com/ticket/16554#comment:4>
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