Currently our team handles 4 million transactions per day.
The existing search tool hooked upto the database takes forever to return results because of the resultset size,sub-total calculations etc. The reponse time is around ~20mins based on query.
I want to promote Lucene to my manager as a solution to this problem. Are there any Lucene limitation i need to be aware of?

What is the limit on the data index files Lucene can handle? We have to index 4 million trasactions per day. I would like to save as much history as possible. how do i know how much i can handle?