>>> It is relatively easy to downgrade to an earlier release within the >>> same major version. We have not switched to 6.5.1 simply because we >>> have no pressing need for it - Solr 6.3 works well for us. > >> That strikes me as a little bit dangerous, unless your indexes are very >> static. The Lucene index format does occasionally change in minor >> versions. > > Err.. Okay? Thank you for that. I was under the impression that the index > format was fixed (modulo critical bugs) for major versions. This will change > our approach to updating.
*Upgrading* (say 6.3 to 6.5.1) should be fine, because -- as I understand it -- newer Lucene/Solr versions support reading older index formats (up to the previous major version). Older versions reading newer index would be ... difficult. - Bram
