An alternating least square recommendation method, system, and non-transitory computer readable medium, include receiving an existing sparse matrix factorization saved in a data store to incrementally update factorized features when users change ratings of the sparse matrix factorization, determining an update ratio based on the number of changed ratings of the sparse matrix factorization, and updating the users' features by using the existing content ratings of the existing sparse matrix factorization if the update ratio is less than a pre-defined threshold ratio.