Absolute relevancy score for text search

[Jason Weinstein]

Hi,

I have a table with articles and a table with keywords. I would like to maintain a list of the top matching articles for each keyword. One way I can do this is to perform a Full-Text Natural Language Search with each keyword and save the results for matches that have a relevance score above a certain threshold.

However, I would like to maintain the list of top matches for each keyword whenever keywords are modified or added, as well as whenever articles are modified or added.

For the case when a keyword is modified, it seems simple enough: I can re-run the full-text search for that particular keyword.

But I'm uncertain how to handle the case when article content is modified. I could re-run searches for all keywords, but I'm worried this would negatively impact the performance of my server. Firstly, I can't do the following:

SELECT id, MATCH ("<new article conetent>") AGAINST (keyword)
-> FROM keywords;

and even if I could do something like this, I don't think it would work properly because the results of a full-text search are relative to the content of the whole pool of articles.

Is there a way to get an absolute relevance score for each keyword vs. article?

Thanks,

Jason