Looking for a desktop search engine to combine with our project management application we tried several products only to find that none supports permissions on projects. So we wrote our own search engine using PostgreSQL's TSearch2 full text search module. That seemed to work great, until we found that it gets slow with >20k documents. Then we checked Oracle Text and found a similar issue. It seems that the databases needs to check permissions sequentially for each search engine result. Any recommendation to avoid that? Or just keep everything in the RAM of a big big machine?