I plan on building a fulltext search for my website coupled with the porter2 stemming algorithm and a synonym dictionary to expand the results.

I would also like to include spelling suggestions - I think this can be done php's pspell_suggest function or even levenshtein or similar_text.

I've been reading around and some people have suggested that using php for this on a large database would be a massive memory drain - I haven't been able to find much more on it. Is this true? If so what alternatives could I use?