What is the best way to search a phrase that have words that dont all matches, for example:
description = "a cell phone that have an external memory"
and i want to search:
search = "a good phone"
is there any tips using mongodb, or do i use Knuth-Morris-Pratt string matching from python (which will kill the server)?
For a simple regular expression search of a mongo db field you can use find with the "$regex" query expression.
In pymongo that would be db.your_collection.find({"description": {"$regex": "<insert regex here>"}}).
This will get you started. As others have stated, MongoDB doesn't necessarily appreciate you beating it up like this. You may need to consider a more robust solution for big time searching.
Please consider the performance implications of doing a regular expression search in your DB.
Read the MongoDB reference here http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-RegularExpressions.