To chime in, in certain cases the memory requirements for 4x (and 5x) are _much_ improved, see: https://lucidworks.com/blog/2012/04/06/memory-comparisons-between-solr-3x-and-trunk/
But as Shawn says, it's not a magic bullet. Solr 5 requires Java 7, so that's one thing to be aware of. Plus, you either have to upgrade your indexes to 4.x, then install/upgrade to 5x or if you want to jump straight from 3x to 5x, you need to re-index from scratch; Solr 5x will not read an index created with Solr 3x. And rather than have a master/slave setup you'll probably want to migrate to SolrCloud as well, it's much easier to create/manage a cluster with shards with SolrCloud. Best, Erick On Wed, Oct 21, 2015 at 12:28 PM, Shawn Heisey <apa...@elyograg.org> wrote: > On 10/21/2015 12:41 PM, Robert Hume wrote: >> I've inherited a project that uses a Solr 3.6.0 deployment. (Several >> masters and several slaves – I think there are 6 Solr instances in total.) >> >> I've been tasked with investigating if upgrading our 3.6.0 deployment will >> improve performance – there’s a lot of data and things are getting slow, >> apparently. >> >> I've read Apache docs that from 3.6.x to 4.x there were improvements in >> scalability and performance. > > Performance does get better in newer versions, but for most use cases, > there is NOT a night/day difference, just a minor speedup. Upgrading > *might* help, but even if it does, chances are that it will not > completely solve the problem. > > The most common reason for Solr performance problems is that there is > not enough memory. That might mean the java heap is a little too small, > but more frequently, it means that there's not enough memory in the > server to cache the index contents effectively. > > General information: > > https://wiki.apache.org/solr/SolrPerformanceProblems > > Solr 3.6.x is very solid software, despite its age. The newest version > is (IMHO) better, but if 3.x (3.6.2 in particular) meets your needs, you > can keep using it. Solr 3.x can run with a very ancient version of Java > -- version 5! I believe that it still works even in Java 8. > >> I see that from 4.x to 5.x that Solr is now a standable server and no >> longer just a WAR running on Tomcat. > > Yes. There's a lot that could be said about that topic. The highlights > are here: > > https://wiki.apache.org/solr/WhyNoWar > > Thanks, > Shawn >
