Aggregation across multiple DRUID datasource

Hello Druid Users,
I understand join is not an priority as of now [1], does anyone have a similar use case needing to join/union across multiple data sources? And if so, how do you tackle the problem? Thanks!



There are two features Druid has that are in this area.

One is union datasources, that lets you query multiple datasources as if they were a single one:

Another is query time lookups, that lets you join small (broadcast in memory) “lookup” tables onto regular datasources: