Polaris is the distributed SQL engine behind Fabric Data Warehouse, bringing SQL Server query processing into a stateless architecture over OneLake.

Based on the Polaris papers, this session explains how T-SQL in SQL Pools is compiled by the Front End nodes, optimized into distributed physical plans, orchestrated by the Distributed Computing Platform as workflow DAGs, and executed by Back End compute nodes over data cells. We connect that engine design to Parquet storage, Delta Lake log publishing, query decorrelation, and snapshot isolation, and show what it means for data movement, concurrency, plan quality, and performance at scale.