Consider what you've seen with Solr search components: highlighting search results, suggesting search spelling corrections, query autocomplete, editorially modifying query results for particular user queries, suggesting documents "more like this", calculating mathematical statistics of indexed numbers, and grouping/collapsing search results. By now, it should be clear why the text search capability of your database is inadequate for all but basic needs. Even Lucene-based solutions don't necessarily have the extensive feature set that you've seen here. You may have once thought that searching was a relatively basic thing, but Solr search components really demonstrate how much more there is to it.

The chapters thus far have aimed to show you the majority of the features in Solr and to serve as a reference guide for them. The remaining chapters don't follow this pattern. In the next chapter, you're going to see numerous ways that applications integrate with Solr. That includes client APIs as well as things like a crawler and Hadoop.