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Yes, but as per the document you can put a MySQL server along with the Data server node and use SQL.

RonDB is a KV store with SQL capabilities (the MySQL storage engine NDB is maintained by Oracle as part of MySQL NDB Cluster). Hopsworks is on top of this adding a new REST API (REST + gRPC) service that is already in the github tree and will ready for production usage in a few months.

FoundationDB is not a SQL database either though.