How does Druid currently deal with nested data columns, and what are the upcoming changes?

This is a fairly common question. Here’s an example. The current way of dealing with nested data columns is by using the flattenSpec. However, there’s something exciting on the horizon.

The community is hard at work on:

building out the capabilities to store nested and structured data directly as it is, and query nested fields within this structure without sacrificing the performance available to queries operating on traditional Druid flattened columns.

Read all about it here. If you’re interested in becoming a committer, read this.