When monitoring production environments, logging about specific N1QL queries that are failing would be very helpful. Queries might be problematic due to bad statement syntax, targeting the wrong/missing bucket, missing index, inefficient index causing a timeout, etc.
This log would only apply If the failure is related to the query itself (i.e. not just an HTTP communication error). Logging the actual query text that failed would help with identifying bad query and locating it in code.
The Warn log level is probably the most appropriate for this log.
NOTE: I renamed the ticket from
Log failed N1QL queries to assist with production monitoring
Do not log failed N1QL prepare queries