Hi all, I am using a left join to join two collections:
PCollection<KV<String, Map<String, String>>> p1 = ... PCollection<KV<String, Map<String, String>>> p2 = ... Join.leftOuterJoin(p1, p2, Collections.emptyMap()) My question is: how do we provide a null value which matches the schema of the p2 PCollection if we don't know the schema? If the Map in p1 consists of some keys including "a", and the Map in p2 contains key "a" as well as some other keys (which are not in p1), what is the best way to ensure the null value contains all the keys from the Map in p2 (with empty String values for those keys)? My current idea is to pull the keys from p2 before the join and use as a side input in a step after the join, but I'm not sure if there is a simpler option. Thanks, Joe
