[model] migrations setup

server/migrations/20191025150506-notifications_index.js

@@ -0,0 +1,15 @@
+'use strict';
+
+module.exports = {
+  up: (queryInterface, Sequelize) => {
+    return queryInterface.addIndex('notifications', {
+      unique: true,
+      fields: ['action', 'type']
+    }).catch(e => {})
+  },
+
+  down: (queryInterface, Sequelize) => {
+    return queryInterface.removeIndex('notifications',
+      ['actions', 'type'])
+  }
+};