I use the real-time DB for my iOS app. Something I do very often is to store some info in a node key for easy access, and to solve some other issues in my code. But I wonder if I would be charged more to do something like that, instead of just storing the data inside the node.
For example, I do the following (saving postID and UID in the key):
Timeline / uid / someUID: postID / Other data here ...
Would I have to pay extra? Would it be cheaper to just use a randomID? Are there any other considerations?