How to arrange data in firebase

Hi all
I am making an application which would have a collection of posts displayed to the user according to the user area. User can select the area and then can see all posts in that area (suburb/city).
How should I arrange data in firebase so that I can load data accordingly without doing much filtering? Should I arrange it like


Where 3000 is the postcode of Melbourne.

You need it as flat as absolutely possible. So as you have at the minute, but if at all possible, don’t nest any data. Firebase can only look at one node at a time, so you want to limit nesting as much as possible.

If you want to optimise, then have a collection of areas as well, each area should have an array of IDs from your first collection. This means you need to read/write two things, but the reads will be highly optimised (no filtering necessary). Use this pattern as much as possible (normalisation).