The performance of an application is one of the most important factors. Of course, there are other factors such as usability and availability—we can recite much more, but one of the most crucial and major factors is the performance. Even if our application is perfectly done in terms of usability, the users won't be able to use it if they have to wait for minutes for the search results.

The standard Solr deployment is fast enough, but sooner or later a time will come when you will have to optimize your deployment. The recipes in this chapter will try to help you optimize Solr deployment.

If your business depends on Solr, you should keep monitoring it even after optimization. You can see how your environment works, the state of Solr nodes, the number of queries that run, its speed, and so on. There are numerous solutions available on the market, from the generic and open sourced ones such as Ganglia (http://ganglia.sourceforge.net/) to specific ones such as SPM Performance Monitoring & Alerting (http://www.sematext.com/spm/index.html) from the Sematext group.