Fix debian structured copy with large content queries

pulp_deb/app/tasks/copy.py

@@ -41,11 +41,14 @@ def find_structured_publish_content(content, source_repo_version):
     prc_qs = PackageReleaseComponent.objects.filter(pk__in=prc_content_qs.only("pk"))
 
     # ReleaseComponents:
+    release_components = prc_qs.values_list(
+        "release_component_id", "release_component__distribution"
+    ).distinct()
     release_component_ids = set()
     distributions = set()
-    for prc in prc_qs.select_related("release_component").iterator():
-        release_component_ids.add(prc.release_component.pk)
-        distributions.add(prc.release_component.distribution)
+    for release_component_id, distribution in release_components:
+        release_component_ids.add(release_component_id)
+        distributions.add(distribution)
 
     release_component_content_qs = source_repo_version.content.filter(
         pk__in=release_component_ids

pulp_deb/tests/unit/test_copy.py

@@ -0,0 +1,50 @@
+from uuid import UUID
+
+import pytest
+
+from pulp_deb.app.models import (
+    AptRepository,
+    Package,
+    PackageReleaseComponent,
+    ReleaseComponent,
+)
+from pulp_deb.app.tasks.copy import find_structured_publish_content
+
+
+@pytest.mark.django_db
+def test_structured_copy_handles_query_exceeding_psycopg_parameter_limit():
+    repository = AptRepository.objects.create(name="oversized-copy-source")
+
+    package = Package.objects.create(
+        package="test-package",
+        version="1.0",
+        architecture="amd64",
+        relative_path="pool/t/test-package/test-package_1.0_amd64.deb",
+        sha256="a" * 64,
+    )
+    release_component = ReleaseComponent.objects.create(
+        distribution="stable",
+        component="main",
+    )
+    package_release_component = PackageReleaseComponent.objects.create(
+        package=package,
+        release_component=release_component,
+    )
+
+    with repository.new_version() as source_version:
+        source_version.add_content(Package.objects.filter(pk=package.pk))
+        source_version.add_content(
+            PackageReleaseComponent.objects.filter(pk=package_release_component.pk)
+        )
+        source_version.add_content(ReleaseComponent.objects.filter(pk=release_component.pk))
+
+    # Reproduce content selection large enhough to exceet postgres limits
+    # when evaluating through a server side cursor.
+    content_pks = [UUID(int=value) for value in range(1, 65_537)]
+    content_pks.append(package.pk)
+    content = source_version.content.filter(pk__in=content_pks)
+
+    result = find_structured_publish_content(content, source_version)
+    assert result.filter(pk=package.pk).exists()
+    assert result.filter(pk=package_release_component.pk).exists()
+    assert result.filter(pk=release_component.pk).exists()