See the discussion at the bottom of Bug 1389446.
Currently, Mahara is using Elastica version 2.0 for our Elasticsearch PHP library. The Elastica project uncoupled their version numbers from Elasticsearch's version numbers with the 2.0 release, so Elastica 2.0 was written to support Elasticsearch 1.5.
However, there doesn't seem to be anywhere in the Mahara documentation that specifies *which* version of Elasticsearch we support. Even the README.Mahara file in htdocs/lib/elastica doesn't say it! So, we should really document that somewhere. Possibly in Mahara's main README, and/or the Elastica README, maybe even on the elasticsearch plugin's config page.
In fact... maybe it would be a good idea if the elasticsearch plugin was able to sniff the elasticsearch version and tell you that it's not a compatible version? Of course, that does rely on the version detection system of Elasticsearch being backwards compatible.
On a related note, we should also upgrade our Elastica version.
For the record, in Mahara 15.10 we use Elastica 2.0.0, which supports up to Elasticsearch 1.5.2: http://
In 15.04 to 1.8 we were using Elastica 0.90.1, which supports up to Elasticsearc 0.90.1: http://