you really should give a lucene inspired solution a try. This would be either ferret or solr. A main difference between these solutions is that you would need a java server like tomcat or jetty running the solr instance. You’ll be able to run ferret without this requirement as it is a superfast c implementation of a fulltext index inspired by lucene indexes and has great ruby and rails bindings. Check out the already cited project site of acts_as_ferret. If you are already running a java server or are familiar with setting up one and maybe want to use your fulltext index from legal java proggies as well solr would be a perfect fit.