Indexing for later full text search in Rails 3

I am working on an application, where then need is to index the data without storing it to database.

When I initialize an abject it should index it. Consider there is a pages table with fields page_title,开发者_如何学Go tags, content. The last field content may have a large amount of text data(some times in MBs). Which is not going to be used for processing at all.

My objective is to index that data without saving it to database. I mean only pages, page_title, tags will be saved into the DB and indexed as well, and content will be indexed only.

I am open to use any full-text search plugin/gem

Implemented this using ultrasphinx. I am indexing by manually generating xml docs for sphinx.