Fix migration by handling empty result sets

db/post_migrate/20220204194347_encrypt_integration_properties.rb

@@ -8,7 +8,7 @@ class EncryptIntegrationProperties < Gitlab::Database::Migration[1.0]
 
   def up
     queue_background_migration_jobs_by_range_at_intervals(
-      define_batchable_model('integrations'),
+      define_batchable_model('integrations').all,
       MIGRATION,
       INTERVAL,
       track_jobs: true,

lib/gitlab/background_migration/encrypt_integration_properties.rb

@@ -64,6 +64,8 @@ module Gitlab
           "(#{record.id}, #{bytea(encrypted_properties)}, #{bytea(encrypted_properties_iv)})"
         end
 
+        return if values.empty?
+
         Integration.connection.execute(<<~SQL.squish)
           WITH cte(cte_id, cte_encrypted_properties, cte_encrypted_properties_iv)
             AS #{::Gitlab::Database::AsWithMaterialized.materialized_if_supported} (

spec/migrations/20220204194347_encrypt_integration_properties_spec.rb

@@ -18,18 +18,18 @@ RSpec.describe EncryptIntegrationProperties, :migration, schema: 20220204193000
     record1 = integrations.create!(properties: some_props)
     record2 = integrations.create!(properties: some_props)
     record3 = integrations.create!(properties: some_props)
-
-    # no update required
-    integrations.create!(properties: nil)
+    record4 = integrations.create!(properties: nil)
+    record5 = integrations.create!(properties: nil)
 
     Sidekiq::Testing.fake! do
       freeze_time do
         migrate!
 
         expect(described_class::MIGRATION).to be_scheduled_migration(record1.id, record2.id)
-        expect(described_class::MIGRATION).to be_scheduled_migration(record3.id, record3.id)
+        expect(described_class::MIGRATION).to be_scheduled_migration(record3.id, record4.id)
+        expect(described_class::MIGRATION).to be_scheduled_migration(record5.id, record5.id)
 
-        expect(BackgroundMigrationWorker.jobs.size).to eq(2)
+        expect(BackgroundMigrationWorker.jobs.size).to eq(3)
       end
     end
   end