If you are already using DIH, then you can use a deltaQuery to find "updated" documents and index only them.
https://cwiki.apache.org/confluence/display/solr/Uploading+Structured+Data+Store+Data+with+the+Data+Import+Handler Some people just parameterize their main DIH query and use request params to control which documents get indexed when doing a "full build"... https://wiki.apache.org/solr/DataImportHandlerDeltaQueryViaFullImport -Hoss http://www.lucidworks.com/
