We went through the internals of Solr and Lucene. We saw how a scorer works on an inverted index and how the DisMax parser works in finding and ranking a result set. We understood the algorithms that work within Lucene when we use the OR or AND clause in Solr. We saw how filters work during the scoring of documents within a result set and the importance and usage of the minimum match parameter.

In the second half of the chapter, we built our own query parser. We went through the concepts of the parboiled parser API and built a SWAN query parser using the API. We also understood what is required during indexing and search to integrate and use the SWAN query parser as a plugin in Solr. This also cleared our concepts of building a custom query parser plugin for Solr.

In the next chapter, we will be looking at the use of Solr in processing and handling big data problems.