in your article you describe Xapian as "not recommended". I think this is mistaken. Xapian is one of the most powerful, high performance, flexible, open source search+indexing systems around. Benefits include:

1. the ability to do real-time (re)-indexing on added/modified/deleted documents.


2. bindings for many programming languages
   
3. based on sound theoretical basis
   
4. stemmers for many human languages:
   http://www.xapian.org/docs/stemming.html
   

Xapian is in successful use on many websites. One I have personal experience of is http://www.theyworkforyou.com/. Try out the search of this large database and see how fast it is.

You also state that Xapian "is not PHP5 compatible" but then 2 sentences later mention a "PHP 5-compatible Xapian extension". Although I have not used it in PHP5 myself, there appear to be several people who have used Xapian successfully in PHP5:

1. http://blog.dixo.net/2006/04/04/xapian-php5-wrapper/


2. http://article.gmane.org/gmane.comp.search.xapian.general/2673
   (link broken at time of writing, so google cache version:)


3. http://66.102.9.104/search?q=cache:-lKeWzlSLZAJ:article.gmane.org/gmane.comp.search.xapian.general/2673+http://article.gmane.org/gmane.comp.search.xapian.general/2673&hl=en&ct=clnk&cd=1&gl=fr&client=firefox-a

for an intro read "Homo Xapian - The Search For a Better Search… Engine" in June 2005 PHP Architect:
https://www.phparch.com/issue.php?mid=59

David Heath