Firebase分页下载全库

Question

I am using firebase pagination to limit the firebase database downloads but the firebase console still shows lots of database downloads,

DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("Posts").child(country).child(phase);

query = db.orderByChild("random_no").startAt(min).limitToFirst(limit);

FirebaseRecyclerOptions<Photo> options =
                new FirebaseRecyclerOptions.Builder<Photo>()
                        .setQuery(query, Photo.class)
                        .build();

I hope it downloads the whole database before pagination.

Can anyone help how to do firebase pagination without downloading whole database.

Answer 1

If you tell the Firebase data to order/filter its results, it will always do so. It can only do this on the server however, if you've defined the necessary index in the rules of your database. If no such index is found, the SDK will download all the nodes at the path, and order/filter them in the application itself. If this happens, it will also log a warning with instructions on what index to add to your logcat output.

So most likely you didn't define an index on random_no for /Posts/$country/$phase in your database rules.