A multi-tenant system comprises a monolithic database storing global records, each including global fields common for all tenants; a custom field database storing custom records, each including custom fields for a tenant; a custom field record service processing a custom record storage request by instructing the custom field database to store custom field values of the custom record for the tenant, and processing a custom record fetch request by instructing the custom field database to retrieve the custom field values; a monolithic application configured to receive a record storage or fetch request, configured to partition the record storage request into the global record storage request and the custom record storage request, configured to send the custom record storage request to the custom field record service, configured to partition the record fetch request into the global record fetch request and the custom record fetch request, and configured to send the custom record fetch request to the custom field record service.