In big clusters with many jdbc/odbc users, in order to save resources are often implemented scripts that automatically cancel queries (e.g. long running queries) (the scripts typically are using the Impala Webui).
- A jdbc/odbc client submit a query
- The Coordinator start the query execution
- The query is cancelled from the Coordinator WebUi
- The jdbc/odbc client ask to the Coordinator the query status (GetOperationStatus)
- The Coordinator answer "unknown query ID" (as the query was cancelled)
- For the client perspective the query failed for "unknown query ID"
Currently, if a running query is cancelled from the impalad WebUI, the client will just receive an 'unknown query ID' error on the next fetch/getOperationStatus attempt. It would be good to be able to explicitly call out this case.