Great work on this, Alexandr. I've been thinking a lot about doing joins in Django to subqueries. As you point out, when you are doing several subquery annotations of the same subquery, just with different columns, that can really hurt performance. Currently, I've been recommending doing a JSON object as the subquery column.
I really like the idea of an explicit join to a subquery, as it can perform significantly better - in the case where most of the rows share the same subquery, the database can perform the subquery once per distinct row joined, rather than once for each row. I think, instead of using a `JoinedSubquery`, we should just make it that a `Subquery`, containing unresolved OuterRef instances, can also be resolved by doing a `QuerySet.join(Subquery(...))`. We could also have a lateral argument that allowed a LATERAL JOIN to a subquery, but perhaps that's later down the track. (Actually, now I think about it, a QuerySet should probably just act as a Subquery when it's used as one, but perhaps that's too magic). Matt. -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/2bec9c0d-574c-493a-bbe2-fa58ccccab56%40googlegroups.com.
