Fix orphan temp table untracked_files_for_uploads

lib/gitlab/background_migration/prepare_untracked_uploads.rb

@@ -43,7 +43,11 @@ module Gitlab
         store_untracked_file_paths
-        schedule_populate_untracked_uploads_jobs
+        if UntrackedFile.all.empty?
+          drop_temp_table
+        else
+          schedule_populate_untracked_uploads_jobs
+        end
       end
       private
@@ -165,6 +169,11 @@ module Gitlab
         bulk_queue_background_migration_jobs_by_range(
           UntrackedFile, FOLLOW_UP_MIGRATION)
       end
+
+      def drop_temp_table
+        UntrackedFile.connection.drop_table(:untracked_files_for_uploads,
+                                            if_exists: true)
+      end
     end
   end
 end

spec/lib/gitlab/background_migration/prepare_untracked_uploads_spec.rb

@@ -8,8 +8,6 @@ describe Gitlab::BackgroundMigration::PrepareUntrackedUploads, :sidekiq do
   before do
     DatabaseCleaner.clean
-
-    drop_temp_table_if_exists
   end
   after do
@@ -44,27 +42,6 @@ describe Gitlab::BackgroundMigration::PrepareUntrackedUploads, :sidekiq do
     end
   end
-  it 'ensures the untracked_files_for_uploads table exists' do
-    expect do
-      described_class.new.perform
-    end.to change { ActiveRecord::Base.connection.table_exists?(:untracked_files_for_uploads) }.from(false).to(true)
-  end
-
-  it 'has a path field long enough for really long paths' do
-    described_class.new.perform
-
-    component = 'a' * 255
-
-    long_path = [
-      'uploads',
-      component, # project.full_path
-      component  # filename
-    ].flatten.join('/')
-
-    record = untracked_files_for_uploads.create!(path: long_path)
-    expect(record.reload.path.size).to eq(519)
-  end
-
   context "test bulk insert with ON CONFLICT DO NOTHING or IGNORE" do
     around do |example|
       # If this is CI, we use Postgres 9.2 so this whole context should be
@@ -90,6 +67,21 @@ describe Gitlab::BackgroundMigration::PrepareUntrackedUploads, :sidekiq do
         UploadService.new(project2, uploaded_file, FileUploader).execute
       end
+      it 'has a path field long enough for really long paths' do
+        described_class.new.perform
+
+        component = 'a' * 255
+
+        long_path = [
+          'uploads',
+          component, # project.full_path
+          component  # filename
+        ].flatten.join('/')
+
+        record = untracked_files_for_uploads.create!(path: long_path)
+        expect(record.reload.path.size).to eq(519)
+      end
+
       it 'adds unhashed files to the untracked_files_for_uploads table' do
         described_class.new.perform
@@ -235,10 +227,10 @@ describe Gitlab::BackgroundMigration::PrepareUntrackedUploads, :sidekiq do
   # Very new or lightly-used installations that are running this migration
   # may not have an upload directory because they have no uploads.
   context 'when no files were ever uploaded' do
-    it 'does not add to the untracked_files_for_uploads table (and does not raise error)' do
+    it 'deletes the `untracked_files_for_uploads` table (and does not raise error)' do
       described_class.new.perform
-      expect(untracked_files_for_uploads.count).to eq(0)
+      expect(untracked_files_for_uploads.connection.table_exists?(:untracked_files_for_uploads)).to be_falsey
     end
   end
 end