In S3 each file is identified with a full path. Not only you cannot rename a single file, but you also cannot rename a "folder" (because that would imply a bul

In S3 each file is identified with a full path. Not only you cannot rename a single file, but you also cannot rename a "folder" (because that would imply a bulk rename on a large number of children of that "folder") This is the fundamental difference between a first class folder and just a convention on prefixes of full path names. If you don't allow renames, it doesn't really make sense to have each "folder" store the list of the children. You can instead have a giant ordered map (some kind of b-tree) that allows you for efficient lookup and scanning neighbouring nodes.