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Update manual to explain JoinQueryset instead of JoinManager

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Maarten ter Huurne 2024-04-17 17:28:25 +02:00
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15
docs/managers.rst
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@ -86,11 +86,11 @@ it's safe to use as your default manager for the model.
.. _contributed by Jeff Elmore: https://jeffelmore.org/2010/11/11/automatic-downcasting-of-inherited-models-in-django/
JoinManager
-----------
JoinQueryset
------------
The ``JoinManager`` will create a temporary table of your current queryset
and join that temporary table with the model of your current queryset. This can
A ``JoinQueryset`` will create a temporary table containing its own query result
and join that temporary table with the model it is querying. This can
be advantageous if you have to page through your entire DB and using django's
slice mechanism to do that. ``LIMIT .. OFFSET ..`` becomes slower the bigger
offset you use.
@ -102,8 +102,9 @@ offset you use.
# qs contains 10 objects, and there will be a much smaller performance hit
# for paging through all of first 2000 objects.
Alternatively, you can give it a queryset and the manager will create a temporary
table and join that to your current queryset. This can work as a more performant
Alternatively, you can give it another queryset and ``JoinQueryset`` will create
a temporary table containing the result of the given queryset and
join that temporary table to itself. This can work as a more performant
alternative to using django's ``__in`` as described in the following
(`StackExchange answer`_).
@ -114,6 +115,8 @@ alternative to using django's ``__in`` as described in the following
.. _StackExchange answer: https://dba.stackexchange.com/questions/91247/optimizing-a-postgres-query-with-a-large-in
You can create a manager that produces ``JoinQueryset`` instances using ``JoinQueryset.as_manager()``.
.. _QueryManager:
QueryManager