The target technology for the database is fhirbase, itself installed on a Postgres database and making use of JSONB feature to implement the expected entity extensibility mechanism.
Note:
fhirbase is open source, under MIT license. Yet extensions like fhirpath seem not to be in MIT license fhirbase extensions.
Other database support:
SQL-Server
Existing implementation of openIMIS make use of SQL-Server database.
The migration strategy puts the database migration to final stages (to ensure an iterative approach).
Early version of openIMIS will thus remain on SQL-Server, but phase 2 of the Transformation methodology is dedicated to switch to Postgres.
Other
FHIR implementation (fhirbase) only supports Postgres as database platform. No other database engine (Oracle, DB2, MongoDB,...) will be supported.