Add FAQ about slow joins #320
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timgraham
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Jun 19, 2025
| Querying across relational fields like :class:`~django.db.models.ForeignKey` and :class:`~django.db.models.ManyToManyField` is really slow. Is there a way to improve the speed of these joins? | ||
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| Not really. Joins use MongoDB's :doc:`$lookup |
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Re: "Not really."
We could mention the possibility of using raw_aggregate() to manually construct a query as mentioned in #309, but I think that's unlikely to be an attractive and maintainable solution for most projects.
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🤔 we could, the people then will ask: why aren't you doing that approach?
The answer is: because we have to modify the django query tree or handle this particular case differently. IMO keep this as it is now, otherwise we should explain the limitations that we have in this particular case.
WaVEV
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Jun 25, 2025
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Some discussion in #309.