dtSearch Engine f/Linux 3-Server Pack ***Requires C++ or Java programming.***
dtSearch - INSTANTLY SEARCH TERABYTES OF TEXT
25+ metadata and full-text search options with highlighted hits
Numerous advanced data classification options, including faceted search dtSearch's own document filters support Office, PDF, HTML, XML, ZIP, emails (with nested attachments), and many other data types; supports SQL and similar databases
Linux version provides C++ and Java APIs
dtSearch Engine also available for multiple other platforms.
See dtSearch.com site for hundreds of reviews and case studies available; articles on faceted search and other topics; and fully-functional evaluations.
Server definition: License covers usage in a single organization. Each physical machine, including all load balancing, backup, testing and development machines, counts as a server for licensing. In a cloud-based environment, each instance count`s as a server for licensing.