Have you looked at CHANGES.txt in <SOLR_HOME>? It has upgrade instructions for every release. Note that in general, newer Solr will *read* an older index (one major revision back. i.e. 3.x should read 1.x, but 4.x will not read 1.x. Note also that there was no 2.x solr).
The cautions in the upgrade notes are really about making sure that an index *produced* with 3.x is not *read* by 1.4, i.e. don't upgrade the master before the slave. I *think* that as long as you upgrade *all* slaves before upgrading the master, you'll be fine. And I also believe that you can upgrade only some of the slaves. Each of the slaves, even if only some of them are upgraded, are reading a 1.4 index even after replications. But I'd test first. And if you can re-index, that would actually be the best solution. However, as above you can't reindex until *all* the slaves are upgraded. Best Erick On Fri, Dec 23, 2011 at 7:41 AM, Bhavnik Gajjar <bhavnik....@gmail.com> wrote: > Greetings, > > We are planning to migrate from Solr 1.4 to Solr 3.5 (or, even new Solr > version than 3.5, when available) in coming days. There are few questions > about this migration. > > > • I heard, index format is changed in this migration. So, does this require > me to reindex millions of data? > > • Are there any migration tool (or any other means?) available that would > convert old indexes (1.4) to new format (3.5)? > > • Consider this case. > http://myserver:8080/solr/mainindex/select/?q=solr&start=0&rows=10&shards=myserver:8080/solr/index1,myserver:8080/solr/mainindex,remoteserver:8080/solr/remotedata. > In this example, consider that 'myserver' has been upgraded with Solr 3.5, > but 'remoteserver' is still using Solr 1.4. The question is, would data > from remoteserver's Solr instance come/parsed fine or, would it cause > issues? If it results into issues, then of what type? how to resolve them? > Please suggest. > > • We are using various features of Solr like, searching, faceting, > spellcheck and highlighting. Will migrating from 1.4 to 3.5 cause any break > in functionality? is there anything changed in response XML format of here > mentioned features? > > Thanks in advance, > > Bhavnik > **
