Druid can only do left and inner joins, and joining against other fact tables is currently not supported.
When should you not use druid?
Situations where you would likely not want to use Druid include:
- You need low-latency updates of existing records using a primary key. ...
- You are building an offline reporting system where query latency is not very important.
What SQL does Druid use?
Apache Druid supports two query languages: Druid SQL and native queries. This document describes the SQL language. Druid SQL is a built-in SQL layer and an alternative to Druid's native JSON-based query language, and is powered by a parser and planner based on Apache Calcite.
