Improve error reporting in the API

[yurishkuro]

The message says "and 1 failure" but does not specify what it was.

[vprithvi]

I looked into this - the query object only contains the string and not the failure. It seems that Cassandra logs might have the failure.

I'll put out a diff to log the query

[yurishkuro]

string would be enough if it actually contained the error. We're currently swallowing the error message somewhere.

[vprithvi]

We're currently swallowing the error message somewhere.

The error message from C* is "Operation failed - received 0 responses and 1 failures"

[yurishkuro]

Interesting. We should at least wrap it with "error from Cassandra: %s" to avoid guessing whether the message is from. Otherwise, seems like a fix needed in Cassandra itself. Would be nice to trace into Cassandra calls.