PostgreSQL is not supported as has been extensively discussed in previous OMBs.
Please refer to the following sites for details:
https://ec.europa.eu/digital-building-blocks/sites/display/EDELCOMMUNITY/PostgreSQL.
https://ec.europa.eu/digital-building-blocks/tracker/browse/EDELGOV-10
https://ec.europa.eu/digital-building-blocks/tracker/browse/EDELGOV-33