Here is some AWS documentation on it:

https://docs.aws.amazon.com/AmazonS3/latest/userguide/optimi...

> For example, your application can achieve at least 3,500 PUT/COPY/POST/DELETE or 5,500 GET/HEAD requests per second per prefix in a bucket. There are no limits to the number of prefixes in a bucket. You can increase your read or write performance by using parallelization. For example, if you create 10 prefixes in an Amazon S3 bucket to parallelize reads, you could scale your read performance to 55,000 read requests per second.

Related to your question, even if we just stick to `/` because it seems safer, does that mean that "foo/bar/baz/1/" and "foo/bar/baz/2/" are two prefixes for the point of these request speed limits? Or does the "prefix" stop at the first "/" and files with these keypaths are both in the same "prefix" "foo/"?

Note there was (according to docs) a change a couple years ago that I think some people haven't caught on to:

> For example, previously Amazon S3 performance guidelines recommended randomizing prefix naming with hashed characters to optimize performance for frequent data retrievals. You no longer have to randomize prefix naming for performance, and can use sequential date-based naming for your prefixes.

The ListObjects api will omit all objects that share a prefix that ends in the delimiter, and instead put said prefix into the CommonPrefix element, which would be reflected as PRE lines. (So with a delimiter of '/', it basically hides objects in "subfolders", but lists any subfolders that match your partial text in the CommonPrefix element).

By default `aws s3 ls` will not show any objects within a CommonPrefix but simply shows a PRE line for them. The cli does not let you specify a delimiter, it always uses '/'. To actually list all objects you need to use `--recursive`.

The output there would suggest that bucket really did have object names that began with `bar-folder/`, and that last line did not list them out because you did not include the trailing slash. Without the trailing slash it was just listing objects and CommonPrefixes that match the string you specified after the last delimiter in your url. Since only that one common prefix matched, only it was printed.