Solr Near Realtime Search for versions 3.5/3.4/3.3/3.2/1.4.1

Near Real Time Search for Solr 3.5/3.4/3.3/3.2 and 1.4.1 is available with RankingAlgorithm. NRT enables you to search concurrently while adding/updating documents, finding the new documents in real time. There is no need to commit. As there is no commit, the indexing is fast and an update performance of about 5,000 documents in about 498 ms has been observed with the MBArtists index (390k documents) on a two core Linux system with one concurrent searcher. You can get more information from here,

Note: For NRT with Solr 4.0, please see