This document discusses Indicium, a system for enabling interactive querying at scale on Spark. It describes a unified data platform using Spark for storing and processing data, as well as enabling scheduled jobs, BI reports, and real-time lookups. It then discusses two parts of Indicium: (1) a managed context pool using Apache Zeppelin and Spark Job Server for multi-user SQL queries, and (2) a smart query scheduler for dynamic scheduling, load balancing, and high availability of queries. The smart scheduler aims to improve on the managed context pool by addressing issues like FIFO scheduling and lack of failure handling.