Search engines are usually based on a special structure, called inverted index, which is used to answer queries quickly. There are two disadvantages resulting from this approach. First, the inverted index structure most be constructed prior to searching it, and secondly, the index structure takes up additional space on a computer's hard-disk. However, both problems mentioned above are negligible, if an index is queried a few hundred times a day, and can be used to find information that would otherwise be lost in the depths of a pile of documents.
An inverted index is a well researched and understood structure. It is documented and discussed in a few research papers and books, such as MG ("Managing Gigabytes").
These pages begin with a tutorial overview of using Zettair. Then they document in more detail how you to use Zettair to build an index and how to query that index. There are also some pointers for those wishing to hack the Zettair source code.
Feel free to drop us (the Search Engine Group) a line at email@example.com if you have any questions or comments. Or visit the Zettair home page for more information.