Lookups Query Performance

Hi folks,

I have a datasource with quite a few dimensions in it. I started exploring lookups with the intent of moving them out for 2 reasons -

  1. Allow dimensional updates seamlessly (without updating historical data in Druid).
  2. Reduce the average size of a segment.

While running a GroupBy query (with the grouping on the lookup column), I’m noticing a significant performance degradation. Queries that take less than 1 second without lookups are taking up to 4-5 seconds with lookups.

Has anyone faced such an issue? Any suggestions to mitigate this?

Hi Guys, any response will be much appreciated.

Where is your lookup dimensions stored?