perf(RHINENG-24466): skip host_count query during MQ ingestion

lib/group_repository.py

@@ -576,27 +576,25 @@ def get_ungrouped_group(identity: Identity) -> Group:
     return ungrouped_group
 
 
-def serialize_group(group: Group | dict, org_id: str, account: str | None = None) -> dict:
+def serialize_group(
+    group: Group | dict, org_id: str, account: str | None = None, *, with_host_count: bool = True
+) -> dict:
     """
-    Serialize a group with host count.
+    Serialize a group, optionally including host count.
     Delegates to the appropriate serializer based on whether the group is from the database or RBAC v2.
 
     Args:
         group: Either a Group ORM object (from DB) or a dict (from RBAC v2)
         org_id: The organization ID
         account: The account_number (optional, only used for RBAC v2 workspaces)
-
-    Returns:
-        Dictionary containing serialized group data with host_count
+        with_host_count: When False, skip the host count query (used during MQ ingestion
+            where an accurate count is not needed and the query is expensive).
     """
     if isinstance(group, dict):
-        # RBAC v2 workspace (dict from RBAC API)
-        # Extract group_id from dict and get host count using batch function
         group_id = group["id"]
-        host_count = get_host_counts_batch(org_id, [group_id])[group_id]
+        host_count = get_host_counts_batch(org_id, [group_id])[group_id] if with_host_count else 0
         return serialize_rbac_workspace_with_host_count(group, org_id, account, host_count)
     else:
-        # Database Group (ORM object)
         group_id = str(group.id)
-        host_count = get_host_counts_batch(org_id, [group_id])[group_id]
+        host_count = get_host_counts_batch(org_id, [group_id])[group_id] if with_host_count else 0
         return serialize_db_group_with_host_count(group, host_count)

lib/host_repository.py

@@ -90,7 +90,9 @@ def add_host(
         matched_host = find_existing_host(identity, canonical_facts)
 
     group = get_or_create_ungrouped_hosts_group_for_identity(identity)
-    input_host.groups = [serialize_group(group, identity.org_id, getattr(identity, "account_number", None))]
+    input_host.groups = [
+        serialize_group(group, identity.org_id, getattr(identity, "account_number", None), with_host_count=False)
+    ]
 
     if matched_host:
         defer_to_reporter = operation_args.get("defer_to_reporter")

tests/test_models.py

@@ -2838,3 +2838,46 @@ def test_update_display_name_writes_when_reporter_changed(db_create_host, models
 
     assert existing_host.display_name == "my-host"
     assert existing_host.display_name_reporter == "yupana"
+
+
+def test_serialize_group_with_host_count_false(flask_app, mocker):  # noqa: ARG001
+    """serialize_group(with_host_count=False) should skip the host count query."""
+    from lib.group_repository import serialize_group
+
+    mock_group = mocker.Mock()
+    mock_group.id = "test-group-id"
+    mock_group.name = "Test Group"
+    mock_group.org_id = "test_org"
+
+    count_spy = mocker.patch("lib.group_repository.get_host_counts_batch")
+    mocker.patch(
+        "lib.group_repository.serialize_db_group_with_host_count",
+        return_value={"id": "test-group-id", "name": "Test Group", "host_count": 0},
+    )
+
+    result = serialize_group(mock_group, "test_org", with_host_count=False)
+
+    count_spy.assert_not_called()
+    assert result["host_count"] == 0
+
+
+def test_serialize_group_with_host_count_true(flask_app, mocker):  # noqa: ARG001
+    """serialize_group(with_host_count=True) should query for host count (default behavior)."""
+    from lib.group_repository import serialize_group
+
+    mock_group = mocker.Mock()
+    mock_group.id = "test-group-id"
+
+    count_spy = mocker.patch(
+        "lib.group_repository.get_host_counts_batch",
+        return_value={"test-group-id": 42},
+    )
+    mocker.patch(
+        "lib.group_repository.serialize_db_group_with_host_count",
+        return_value={"id": "test-group-id", "host_count": 42},
+    )
+
+    result = serialize_group(mock_group, "test_org")
+
+    count_spy.assert_called_once()
+    assert result["host_count"] == 42