Remove legacy query to find unsynced LFS objects

This commit removes the legacy queries to find unsynced
LFS objects since we made Foreign Data Wrapper (FDW) a
hard requirement for Geo on GitLab 12.0.

ee/app/finders/geo/legacy_lfs_object_registry_finder.rb

@@ -6,16 +6,6 @@ module Geo
       current_node.lfs_objects.syncable
     end
 
-    def lfs_objects_unsynced(except_file_ids:)
-      registry_file_ids = Geo::FileRegistry.lfs_objects.pluck_file_key | except_file_ids
-
-      legacy_left_outer_join_registry_ids(
-        syncable,
-        registry_file_ids,
-        LfsObject
-      )
-    end
-
     def lfs_objects_migrated_local(except_file_ids:)
       legacy_inner_join_registry_ids(
         current_node.lfs_objects.with_files_stored_remotely,

ee/app/finders/geo/lfs_object_registry_finder.rb

@@ -37,21 +37,11 @@ module Geo
     # You can pass a list with `except_file_ids:` so you can exclude items you
     # already scheduled but haven't finished and aren't persisted to the database yet
     #
-    # TODO: Alternative here is to use some sort of window function with a cursor instead
-    #       of simply limiting the query and passing a list of items we don't want
-    #
     # @param [Integer] batch_size used to limit the results returned
     # @param [Array<Integer>] except_file_ids ids that will be ignored from the query
     # rubocop:disable CodeReuse/ActiveRecord
     def find_unsynced(batch_size:, except_file_ids: [])
-      relation =
-        if use_legacy_queries_for_selective_sync?
-          legacy_finder.lfs_objects_unsynced(except_file_ids: except_file_ids)
-        else
-          lfs_objects_unsynced(except_file_ids: except_file_ids)
-        end
-
-      relation.limit(batch_size)
+      lfs_objects_unsynced(except_file_ids: except_file_ids).limit(batch_size)
     end
     # rubocop:enable CodeReuse/ActiveRecord
 

ee/spec/finders/geo/lfs_object_registry_finder_spec.rb

@@ -797,86 +797,6 @@ describe Geo::LfsObjectRegistryFinder, :geo do
       end
     end
 
-    describe '#find_unsynced' do
-      it 'returns LFS objects without an entry on the tracking database' do
-        create(:geo_file_registry, :lfs, file_id: lfs_object_1.id)
-        create(:geo_file_registry, :lfs, :failed, file_id: lfs_object_3.id)
-
-        lfs_objects = subject.find_unsynced(batch_size: 10)
-
-        expect(lfs_objects).to match_ids(lfs_object_2, lfs_object_4, lfs_object_5)
-      end
-
-      it 'excludes LFS objects without an entry on the tracking database' do
-        create(:geo_file_registry, :lfs, file_id: lfs_object_1.id)
-        create(:geo_file_registry, :lfs, :failed, file_id: lfs_object_3.id)
-
-        lfs_objects = subject.find_unsynced(batch_size: 10, except_file_ids: [lfs_object_2.id])
-
-        expect(lfs_objects).to match_ids(lfs_object_4, lfs_object_5)
-      end
-
-      context 'with selective sync by namespace' do
-        before do
-          allow_any_instance_of(LfsObjectsProject).to receive(:update_project_statistics).and_return(nil)
-
-          create(:lfs_objects_project, project: synced_project, lfs_object: lfs_object_1)
-          create(:lfs_objects_project, project: synced_project_in_nested_group, lfs_object: lfs_object_2)
-          create(:lfs_objects_project, project: synced_project_in_nested_group, lfs_object: lfs_object_3)
-          create(:lfs_objects_project, project: unsynced_project, lfs_object: lfs_object_4)
-
-          secondary.update!(selective_sync_type: 'namespaces', namespaces: [synced_group])
-        end
-
-        it 'returns LFS objects without an entry on the tracking database' do
-          create(:geo_file_registry, :lfs, file_id: lfs_object_2.id)
-
-          lfs_objects = subject.find_unsynced(batch_size: 10)
-
-          expect(lfs_objects).to match_ids(lfs_object_1, lfs_object_3)
-        end
-
-        it 'ignores remote LFS objects' do
-          create(:geo_file_registry, :lfs, file_id: lfs_object_2.id)
-          lfs_object_1.update_column(:file_store, ObjectStorage::Store::REMOTE)
-
-          lfs_objects = subject.find_unsynced(batch_size: 10)
-
-          expect(lfs_objects).to match_ids(lfs_object_3)
-        end
-      end
-
-      context 'with selective sync by shard' do
-        before do
-          allow_any_instance_of(LfsObjectsProject).to receive(:update_project_statistics).and_return(nil)
-
-          create(:lfs_objects_project, project: synced_project, lfs_object: lfs_object_1)
-          create(:lfs_objects_project, project: synced_project, lfs_object: lfs_object_2)
-          create(:lfs_objects_project, project: unsynced_project, lfs_object: lfs_object_3)
-          create(:lfs_objects_project, project: project_broken_storage, lfs_object: lfs_object_4)
-          create(:lfs_objects_project, project: project_broken_storage, lfs_object: lfs_object_5)
-
-          secondary.update!(selective_sync_type: 'shards', selective_sync_shards: ['broken'])
-        end
-
-        it 'counts LFS objects that sync has failed' do
-          create(:geo_file_registry, :lfs, file_id: lfs_object_4.id)
-
-          lfs_objects = subject.find_unsynced(batch_size: 10)
-
-          expect(lfs_objects).to match_ids(lfs_object_5)
-        end
-
-        it 'ignores remote LFS objects' do
-          lfs_object_5.update_column(:file_store, ObjectStorage::Store::REMOTE)
-
-          lfs_objects = subject.find_unsynced(batch_size: 10)
-
-          expect(lfs_objects).to match_ids(lfs_object_4)
-        end
-      end
-    end
-
     describe '#find_migrated_local' do
       it 'returns LFS objects remotely and successfully synced locally' do
         create(:geo_file_registry, :lfs, file_id: lfs_object_remote_1.id)