ASPseek

If you are looking for a search engine that can handle a vast number of URLs and perform complex queries, ASPseek may be the solution you need. This software consists of three main components: an indexing robot, a search daemon, and a CGI search frontend.
With ASPseek, you can index millions of URLs and search for specific words and phrases, using wildcards or Boolean operators. Additionally, you can limit your search results by time period, site, or Web space.
The search results can be sorted by relevance (using PageRank) or date. ASPseek is designed to optimize performance when working with multiple sites, thanks to its threaded index, async DNS lookups, and grouping results by site or Web spaces. However, it can also be used for searching a single site.
ASPseek has excellent language support, allowing it to work with multiple languages and encodings simultaneously (including multibyte encodings such as Chinese) thanks to Unicode storage mode.
Other features include stopwords and ispell support, a charset and language guesser, HTML templates for search results, excerpts, and highlighting of query words.
ASPseek is written in C++ and uses a mix of SQL database and binary files for storage. Additionally, it uses the STL library for effective handling of memory and performance. If you need a powerful search engine that can handle complex and diverse requirements, ASPseek may be worth considering.