Interoperability and portability of healthcare data to enable research in the healthcare sector is an important factor towards precision medicine and a learning health system. With many safety-nets put in place like the European General Data Protection Regulation, and local standards like the broad consent set up by the German Medical Informatics Initiative, management and compliance to these standards across all systems and clinical data repositories becomes a daunting task. An appropriate process needs to be established especially when patient data is transferred to and from different systems and standards. On extraction and transforming, an appropriate method of loading the modified data to a destination where it can be read and accessed needs to be established besides functional compliance by the repository systems. This paper makes recommendations in relation to data load strategies while working with FHIR server-based data marts.