First / Last aggregator in ingestion spec


According to the documentation First / Last aggregator is not supported in ingestion spec.
I saw a suggestion in this post to try custom extension to implement this feature.

Please let me know

  1. The reason why it is not supported in ingestion spec?(I am curious as it is not mentioned in documentation)
  2. Is it feasible to implement this feature using a custom extension?

Relates to Apache Druid <0.21.1>

Hey Aravind; the docs entry around First / Last and ingestion is here:

First and Last aggregator cannot be used in ingestion spec, and should only be specified as part of queries.

Re an extension, I suspect that the issue will be that you cannot know the first or last of something if your ingestion is split amongst multiple workers - each worker would have its own view of what is first and what is last… but that is my theory (!) and you may want to post into the devlist and see if anyone has a response that is authoritative :smiley:

1 Like