How to search for most popular topics among documents

Hi

I crawl news feeds and store them in a database but now I want to index them with Lucene to make searches quicker and I also want to populate a list of the most written-about topics in the news articles (documents) of a certain date. In pseudo code I like to say

- Give me a list of the 20 most popular topics among the articles for 2011-04-25.

I plan to have the following fields ID, title, text, date, url

I hope you understand my question

Thanks
Pierre

Hi. So you didn't point about your problems and you just told about your task.
Do you have confuse with this task?