Solr is the popular, blazing fast open source enterprise search platform from the Apache Lucene project. Its major features include powerful full-text search, hit highlighting, faceted search, dynamic clustering, database integration, and rich document (e.g., Word, PDF) handling. Solr is highly scalable, providing distributed search and index replication, and it powers the search and navigation features of many of the world's largest internet sites.
Simple Digital Library makes it easy for your patrons to effectively use your digital collections by enabling you to assign each Dublin Core field a search relevancy. Fields assigned a relevancy of 4 are the most relevant. Fields assigned a relevancy of 1 are the least relevant. You can designate fields as no relevance if you do not want anyone to search these fields.
Facets help patrons quickly understand your collections by breaking your collections into descriptive attributes. Facets enhance the descriptive capacity by going beyond simply naming categories to capturing the dimensions of the item being described. Facets provide a way to filter a huge search result set by the qualities the researchers wants. Combining information from different facets helps your patrons narrow their focus to a manageable set of results which results in getting to the right object faster and more efficiently.