Query tracing

Each query's execution can be traced to see to which nodes it was sent, what operations were performed etc.

First tracing has to be enabled for a query and then its result will contain a tracing id which can be used to query tracing information.

Queries that support tracing:

• Session::query()
• Session::query_iter()
• Session::execute()
• Session::execute_iter()
• Session::batch()
• Session::prepare()

After obtaining the tracing id you can use Session::get_tracing_info() to query tracing information.
TracingInfo contains values that are the same in Scylla and Cassandra®.
If TracingInfo does not contain some needed value it's possible to query it manually from the tables system_traces.sessions and system_traces.events