I mean, what happens if you try to run MapReduceIndexManagement on BigTable. Apparently, you get this error message "MapReduceIndexManagement is not supported for BigTable" but I would like to see the full stack trace leading to this error message, to see where this incompatibility stems from. E.g. the code in:

https://github.com/JanusGraph/janusgraph/blob/d954ea02035d8d54b4e1bd5863d1f903e6d57844/janusgraph-hadoop/src/main/java/org/janusgraph/hadoop/MapReduceIndexManagement.java

reads:
HadoopStoreManager storeManager = (HadoopStoreManager) graph.getBackend().getStoreManager().getHadoopManager();

if (storeManager == null) {

throw new IllegalArgumentException("Store manager class " + graph.getBackend().getStoreManagerClass() + "is not supported");

}

But this is not what you see.

Best wishes,    Marc