Best text search engine for integrating with custom web app?

Question

We have a web app that allows users to upload documents, create their own documents, and so on. Uploaded files are stored on Amazon S3, created information is stored in a My

Answer 1

Lucene is very good. And although it was originally written in java there is a php implementation http://framework.zend.com/manual/en/zend.search.lucene.html