Presto: Auto-discover Cassandra protocol version

[findepi]

Currently io.prestosql.plugin.cassandra.CassandraClientConfig#protocolVersion defaults to V3.
We should automatically select protocol version based on the Cassandra server we're connecting to.

[ebyhr]

fyi: We can get the protocol version using native cassandra session.

select native_protocol_version from system.local;
 native_protocol_version
-------------------------
                       4

https://docs.datastax.com/en/cql/3.3/cql/cql_using/useQuerySystem.html

Or,

ProtocolVersion myCurrentVersion = cluster.getConfiguration()
    .getProtocolOptions()
    .getProtocolVersionEnum();

https://docs.datastax.com/en/developer/java-driver/2.1/manual/native_protocol/

[findepi]

cc @haaawk

[haaawk]

In general you don't have to set the protocol version. When unset, driver will negotiate the highest protocol version supported by both driver and the server.

See https://github.com/datastax/java-driver/blob/3.x/driver-core/src/main/java/com/datastax/driver/core/Cluster.java#L1648

You just need to make sure protocol options in configuration does not have initial protocol version set.

[ebyhr]

https://github.com/prestosql/presto/issues/587 is caused by default protocol version V3. I'll address this issue.

[ebyhr]

We can close this issue now.

[findepi]

Thanks @ebyhr

Done in https://github.com/prestosql/presto/pull/596 (311).