Anthony’s reply:
Lets break it down as if it was SQL. So in SQL you can index 2 columns in the same table, but can you index together two columns together from different tables-No. Or could you index 2 columns where the columns are not only not in the same table, but not even in the same database-of course not, this is getting close. Now the absurd question, could you index across 2 columns that were not just not in the same table or database, but not even on the same server-definatly no. This is how Dgraph distributes. It spreads “columns” across multiple servers. So how exactly do you propose writing an index and updating that index in any kind of performant way when the two predicates that make up the index cannot be ensured that they even coexist on the same server. The index would be more complex to make then refactoring the data to something more feasable.