See SOLR-12281 <https://issues.apache.org/jira/browse/SOLR-12281> for details around the new migration limitation that will be introduced from v8.0. You may be able to get yourself from 4.x to 7.x through clever hoops, but then if you want to upgrade to 8.x later, there is no other way than full re-index. So better plan for a full re-index from the beginning.
-- Jan Høydahl, search solution architect Cominvent AS - www.cominvent.com > 4. okt. 2018 kl. 00:23 skrev Shawn Heisey <apa...@elyograg.org>: > > On 10/3/2018 3:17 PM, Pure Host - Wolfgang Freudenberger wrote: >> Is there any way to migrate cores from 4.10.2 to 7.5.0? I guess not, but >> perhaps someone has an idea. ^^ > > In a word, no. A specific major version of Solr is only guaranteed to read > indexes built and managed *completely* by the previous major version or older > releases in the same major version. But even if you have a supported upgrade > path, my advice is to always build indexes from scratch when upgrading. > > It was recently brought to my attention that upgrades through two major > Lucene versions are NOT guaranteed to work, even if the index is upgraded > through all the major versions one by one with Lucene's IndexUpgrader utility > (or by running an optimize operation within Solr). I was surprised by this, > but the person who said it is someone whose word I have no reason to doubt. > > Thanks, > Shawn >
