apt-xapian-index - Everything you always wanted to index about Debian packages, but were afraid to ask
apt-xapian-index is a maintenance tools for a Xapian index of Debian package information This package provides update-apt-xapian-index, a tool to maintan a Xapian index of Debian package information in /var/lib/apt-xapian-index.
update-apt-xapian-index allows plugins to be installed in /usr/share/apt-xapian-index to index all sorts of extra information, such as Debtags tags, popcon information, package ratings and anything else that would fit.
The index generated by update-apt-xapian-index is self-documenting, as it contains an autogenerated README file with information on the index layout and all the data that can be found in it.
Resources: