We didn't have to re-index when we upgraded - but if you're using a master/slave setup, you won't be able to replicate from a higher version to a lower version - old solr cannot read the new indices.
-----Original Message----- From: roz dev [mailto:rozde...@gmail.com] Sent: Monday, November 14, 2011 7:49 PM To: solr-user@lucene.apache.org Subject: Index format difference between 4.0 and 3.4 Hi All, We are using Solr 1.4.1 in production and are considering an upgrade to newer version. It seems that Solr 3.x requires a complete rebuild of index as the format seems to have changed. Is Solr 4.0 index file format compatible with Solr 3.x format? Please advise. Thanks Saroj
