Intermittent problems with querying data from druid using SQL - druid

Question

I query data from druid via SQL. Sometimes it succeeds, but sometimes it fails. My query uses curl; it is:
curl --negotiate -u:srvadmin -X POST -H'Content-Type: application/json' http://du-s12-idc:8082/druid/v2/sql -d #query.json.
When it fails, I get this response:
{"error":"Unknown exception","errorMessage":"Failure getting results for query[6639c357-441f-456c-9a01-0f7ffd0758b7] url[http://du-s28-idc:8083/druid/v2/] because of [Invalid type marker byte 0x3c for expected value token\n at [Source: (SequenceInputStream); line: -1, column:
1]]","errorClass":"io.druid.java.util.common.RE","host":null}
The file query.json is simple:
{"query":"select * from bds_dsp_media_run_info_h_1016 limit 3"}
The data was loaded from hadoop to druid and succeeded. My druid version was 0.11 and built in a cluster with Kerberos.
Does anyone have this problem?

Answer 1

I think Invalid type marker byte 0x3c... exception is just uninformative response that tells you that the server has an internal error, but doesn't give you a clue on what is actually happening. It would help a lot if you could check broker logs when the request is happening.
But, to play a guessing game - I would expect it to be a Kerberos issue. Do you have KRB5_CLIENT_KTNAME env variable populated with the path to your key file?