I am looking for an open source distributed SQL database system which will distribute the data across nodes but so that there is data redundancy (if one node fails, the data is still available without having to to backup all of the data on each node).
It has to be able to store at least 1 petabyte of data and should have the ability for multiple simultaneous connections, unlike Apache Hadoop.
I searched online for such solutions but most of the distributed databases are noSQL with document structure such as Apache Cassandra but a few options are not open source and free, like CrateDB and CockroachDB.
Please help me with this.