I recently compiled the C++ client (on windows) from master and tested against a 1.9.0 drillbit. The client's behavior does not meet the stable release requirement.
Some API functionalities are broken and should be investigated.
Most noticeable is the getColumns(...) call. It will throw an exception with "Cannot decode getcolumns results" when the number of rows (column records) exceeds a certain number.
I also noticed that: during query execution + data retrieval, if the table is large enough, the result coming back will start to become NULL or empty.
I will see if I can generate some drillclient logs to put in the attachment.
I will also compile and test on other platforms.