1 files changed, 40 insertions, 0 deletions
diff --git a/db/migrate/20180417090132_add_index_constraints_to_internal_id_table.rb b/db/migrate/20180417090132_add_index_constraints_to_internal_id_table.rb
new file mode 100644
index 00000000000..582b89a3948
--- /dev/null
+++ b/db/migrate/20180417090132_add_index_constraints_to_internal_id_table.rb
@@ -0,0 +1,40 @@
+class AddIndexConstraintsToInternalIdTable < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :internal_ids, [:usage, :namespace_id], unique: true, where: 'namespace_id IS NOT NULL'
+
+    replace_index(:internal_ids, [:usage, :project_id], name: 'index_internal_ids_on_usage_and_project_id') do
+      add_concurrent_index :internal_ids, [:usage, :project_id], unique: true, where: 'project_id IS NOT NULL'
+    end
+
+    add_concurrent_foreign_key :internal_ids, :namespaces, column: :namespace_id, on_delete: :cascade
+  end
+
+  def down
+    remove_concurrent_index :internal_ids, [:usage, :namespace_id]
+
+    replace_index(:internal_ids, [:usage, :project_id], name: 'index_internal_ids_on_usage_and_project_id') do
+      add_concurrent_index :internal_ids, [:usage, :project_id], unique: true
+    end
+
+    remove_foreign_key :internal_ids, column: :namespace_id
+  end
+
+  private
+  def replace_index(table, columns, name:)
+    temporary_name = "#{name}_old"
+
+    if index_exists?(table, columns, name: name)
+      rename_index table, name, temporary_name
+    end
+
+    yield
+
+    remove_concurrent_index_by_name table, temporary_name
+  end
+end