Postgres users might find Teodor Sigaev's smlar [1] extension useful for this kind of thing. It implements cosine and other similarity metrics. [1] http://siga

Postgres users might find Teodor Sigaev's smlar [1] extension useful for this kind of thing. It implements cosine and other similarity metrics. [1] http://sigaev.ru/git/gitweb.cgi?p=smlar.git;a=summary http://sigaev.ru/git/gitweb.cgi?p=smlar.git;a=summary