: I can see there is something called a "core" ... it appears there can be : many cores for a single SOLR server. : : Can someone "explain like I'm five" -- what is a core?
https://cwiki.apache.org/confluence/display/solr/Solr+Cores+and+solr.xml "In Solr, the term core is used to refer to a single index and associated transaction log and configuration files (including schema.xml and solrconfig.xml, among others). Your Solr installation can have multiple cores if needed, which allows you to index data with different structures in the same server, and maintain more control over how your data is presented to different audiences." : And how do "cores" differ from 3.x to 5.x. The only fundemental differences between "cores" in Solr 3.x vs 5.x are: 1) in 3.x there was a concept known as the "default core" (if you didn't explicitly use multiple cores) .... with 5.x every request (updates or queries) must be to an explicit core (or collection) 2) when using SolrCloud in 5.x, you should think (logically) in terms of the higher level concept of "collections" which (depending on the settings when the collection is created) may be *implemented* by multiple cores that are managed under the covers for you... https://cwiki.apache.org/confluence/display/solr/SolrCloud https://cwiki.apache.org/confluence/display/solr/Nodes%2C+Cores%2C+Clusters+and+Leaders -Hoss http://www.lucidworks.com/
