How many random elements before MD5 produces collisions?

Question

I\'ve got an image library on Amazon S3. For each image, I md5 the source URL on my server plus a timestamp to get a unique filename. Since S3 can\'t have subdirectories, I

Answer 1

S3 can have subdirectories. Just put a "/" in the key name, and you can access the files as if they were in separate directories. I use this to store user files in separate folders based on their user ID in S3.

For example: "mybucket/users/1234/somefile.jpg". It's not exactly the same as a directory in a file system, but the S3 API has some features that let it work almost the same. I can ask it to list all files that begin with "users/1234/" and it will show me all the files in that "directory".