WIP Improve content_ids handling by defered loading

The array_field can be huge and most of the time we don't need the
values in python. Some uses can even be handled by clever SQL without
ever channelling all the data through the network.

Author: mdellweg

pulpcore/app/models/repository.py

@@ -885,6 +885,10 @@ class Meta:
 class RepositoryVersionQuerySet(models.QuerySet):
     """A queryset that provides repository version filtering methods."""
 
+    def get_queryset(self):
+        # Prevent the content_ids to be automatically hydrated.
+        return super().get_queryset().defer("content_ids")
+
     def complete(self):
         return self.filter(complete=True)
 
@@ -997,15 +1001,13 @@ def get_content(self, content_qs=None):
         if content_qs is None:
             content_qs = Content.objects
 
-        content_ids = self.content_ids
-        if len(content_ids) >= 65535:
-            # Workaround for PostgreSQL's limit on the number of parameters in a query
-            content_ids = (
-                RepositoryVersion.objects.filter(pk=self.pk)
-                .annotate(cids=Func(F("content_ids"), function="unnest"))
-                .values_list("cids", flat=True)
-            )
-        return content_qs.filter(pk__in=content_ids)
+        # Try to not even attempt to evaluate the content_ids on the python side.
+        content_ids_subquery = (
+            RepositoryVersion.objects.filter(pk=self.pk)
+            .annotate(cids=Func(F("content_ids"), function="unnest"))
+            .values_list("cids", flat=True)
+        )
+        return content_qs.filter(pk__in=content_ids_subquery)
 
     @property
     def content(self):