I am building a forum from scratch in PHP. I have used the most of phpBB:s database structure.

But now I am thinking about the search functionality?, what is a good design to be able to search really fast in all posts. I guess there must be some better way than just %query_string% in mysql 🙂

Maybe explode all sentences into words, let the words be keys in a hash table, and the value is a comma separated list of all the post the word is in? Then there is little more trouble if you delete a post but I think that approach is better.

From start I guess I can use the simple solution, but I dont want to change the code when the forum grows bigger.

Thanks for any ideas or if you can point me to the right direction!