After upgrading to Elasticsearch 2.1.1 from 1.5 version, the following warning message started to fill up elasticsearch log:
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [api_version.raw] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [client_addr] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [client_addr.raw] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [forwarded_for] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [forwarded_for.raw] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [proto] returning default postings format
Feb 9 18:25:17 logstash elasticsearch[30011]: [2016-02-09 18:25:17,523][WARN ][index.codec ] [Man-Beast] [logstash-2016.02.09] no index mapper found for field: [proto.raw] returning default postings format```
These warning messages are being pumped into the log almost every seconds and they are always on the same fields (`api_version`, `api_version.raw`, `client_addr`, `client_addr.raw`, `forwarded_for`, `forwarded_for.raw`, `proto`, and `proto.raw`).
I think these warning messages also affect the performance of the cluster as I noticed that the server is somewhat slower after the upgrade.
Any suggestion on how to fix this issue would be greatly appreciated?