phobos182/collectd-elasticsearch — pull request #18 by faxm0dem (2014-10-29 14:13:31+00:00)
Title: Add indices.segments.index_writer_memory and indices.segments.index_memory

From the documentation: "The number of bytes currently in use by the
index buffer"
http://www.elasticsearch.org/blog/performance-considerations-elasticsearch-indexing/
This is available since 1.3.0