xapian (search engine library)

Xapian is an Open Source Search Engine Library, released under 
the GPL. It's written in C++, with bindings to allow use from 
Perl, Python, PHP, Java, Tcl, C#, and Ruby (so far!) Xapian is 
a highly adaptable toolkit which allows developers to easily 
add advanced indexing and search facilities to their own 
applications. It supports the Probabilistic Information 
Retrieval model and also supports a rich set of boolean query 
operators.

The homepage of xapian is found at http://www.xapian.org/

xapian-core does not seem to depend on other packages.
No incompatibilites of the used version are known so far. 
NOTE: Version 0.9.10 works ok with the file search utility recoll,
version 1.0.0 does NOT work with recoll (at the time of writing).
No special configuration is needed after installing the package.