Custom user cloud storage

While Atmos can have millions of objects per listable tag, each object is limited to 127 listable tags, so tagging each song with the users that purchased it would not work.  As an alternative, you could create a "soft link" object, tag it with the user's ID and then use a regular metadata tag to contain the ID of the master song file.  Then you can enumerate all of a user's songs by using their listable tag.

Also note that if you have more than about 64k listable tags, you need to "partition" the tags like a directory structure to keep less than 64k per level , e.g. 12a3f58b -> 12a3/f58b.

Using the above, the "soft link" procedure would look something like this:

String accountId = "12a3/f58b";
String songObjectId = "499ad542a1a8bc200499ad5a6b05580499c3168560a4";
MetadataList mlist = new MetadataList();
mlist.add(new Metadata(accountId, "", true));
mlist.add(new Metadata("SongId", songObjectId, false));
// Add any other song metadata (Title, Artist, etc) here.
atmos.createObject(null, mlist, null, null);

Then to list the songs owned by a user you can use listObjects:

ListOptions options = new ListOptions();
options.setIncludeMetadata(true);
List results = atmos.listObjects(accountId, options);
  
while(results.getToken() != null) {
    // Get more results
    results.addAll(atmos.listObjects(accountId, options));
}

Thank you Jason,

we have decided to keep the reference to our application db.

Do you happen to know what is the maximum length of the object ID?