I am using the real-time olap feature with a lambda datasource definition. When executing a query that has a count(dim_field) in the select clause, where "dim_field" is one of the dimension fields, I get a NPE from org.apache.kylin.stream.core.query.StreamingTupleConverter.
(According to a colleague, a similar query used to work for some time in our environment, and then stopped working, but I can't verify this statement. Restarting the Kylin processes or disabling/enabling the cube does not "fix" the issue.)
The relevant part of stacktrace seems to be:
Caused by: java.lang.NullPointerException at org.apache.kylin.stream.core.query.StreamingTupleConverter.<init>(StreamingTupleConverter.java:86)
Please see attached full stacktrace.