elasticsearch/elasticsearch — pull request #7604 by mikemccand (2014-09-04 22:28:57+00:00)
Title: Don't allow selecting unsupported postings_format / doc_values_format

Today ES allows you to pick e.g. "pulsing", but this is very dangerous because that format, and all other postings/doc values formats from the Lucene codecs module, has no backwards compatibility support in Lucene. So on upgrade you can easily hit strange exceptions that make your index unusable / look like index corruption.

So I removed lucene-codecs JAR entirely from ES, which e.g. removes direct, simple text, memory PF, Lucene's BloomFilteringPF, and disk/memory DVF.

I haven't verified, but I think users can still put the Lucene codecs JAR onto ES's CLASSPATH (e.g. in with a plugin) and then use these formats in their own apps (at their own risk). I think this extra step is better than the ease today with which users can select these formats that Lucene doesn't support.