Solr is an open source search server based on Apache Lucene. Lucene provides Java-based indexing and a search library, and Solr extends it to provide a variety of APIs and search functionality, including faceted search and hit highlighting, and handles Word and PDF document searching. It also provides caching and replication, making it scalable, robust, and very fast.
Happily, Solr also plays nicely with Drupal, the popular CMS platform. If you want fast and effective search on your Drupal site, installing Solr is a straightforward way of getting it quickly. Until this month, the Apachesolr Drupal module didnt support the current Solr 4.x schemas, but as of the very latest version of the Apachesolr module, 7.x-1.2, you can now set up Solr 4.x on your Drupal 7 site. This tutorial assumes that youre running Drupal 7.22 the most up-to-date version under Apache on a Linux box.
via How to set up Solr 4.2 on Drupal 7 with Apache.
If you running Drupal and have a lot of nodes to index and you’re not using Solr you’re missing out on a lot. Though it takes a bit of config to set up, using Solr to index and search your Drupal site is much better than the stock Drupal search.
