Apache Pinot is a realtime distributed OLAP datastore that can answer hundreds of thousands of queries with millisecond latencies. You can head over to https://pinot.apache.org/ to get started with Apache Pinot.
While using any database, we can come across a scenario where a function required for the query is not supported out of the box. In such time, we have to resort to raising a pull request for a new function or finding a tedious workaround.
Scalar Functions that allow users to write and add their functions as a plugin.