Indexing for labels problem

[alihsan-tsdln]

I am implemeting Spark Datasource for JanusGraph. I should fetch data from JanusGraph with Spark DataSource reader. My issue is fetching data from JanusGraph without indexing. It makes me so slow. I should take vertex data by label but I cannot implement indexing on it. What do you recommend for it? Normally, I put property key as "vertex_type" and add same label name on it but for general use datasource I cannot expect same thing from general user. What should I do?