Re: Which hashing algorithm is best to check file duplicity?

Martin Zvarík wrote:

I want to store the file's hash to the database, so I can check next time to see if that file was already uploaded (even if it was renamed). What would be the best (= fastest + small chance of collision) algorithm in this case?

"Fastest" depends mostly on the size of the file, not the algorithm used. A 2gig file will take a while using md5 as it will using sha1. Using md5 will be slightly quicker than sha1 because generates a shorter hash so the trade-off is up to you. $ ls -lh file.gz 724M 2008-07-28 10:02 file.gz $ time sha1sum file.gz 4ae7bd1e79088a3e3849e17c7be989d4a7c97450 file.gz real 0m3.398s user 0m3.056s sys 0m0.336s $ time md5sum file.gz 16cff7b95bcb5971daf1cabee6ca4edd file.gz real 0m2.091s user 0m1.744s sys 0m0.328s $ time sha1sum file.gz 4ae7bd1e79088a3e3849e17c7be989d4a7c97450 file.gz real 0m3.332s user 0m2.988s sys 0m0.344s $ time md5sum file.gz 16cff7b95bcb5971daf1cabee6ca4edd file.gz real 0m2.136s user 0m1.776s sys 0m0.348s -- Postgresql & php tutorials http://www.designmagick.com/