The Breakdown of the Open Lakehouse in 2026: Iceberg, Arrow, Polaris, Parquet, and Ossie, and How to Actually Build One

Table of Contents First, Why “Open” Is the Whole Point How the Stack Came Together Layer One: Apache Parquet, the File Format Layer Two: Apache Iceberg, the Table Format Layer Three: Apache Polaris, the Catalog Layer Four: Apache Arrow, the In-Memory and Transport Layer Layer Five: Apache Ossie, the Semantic Layer How the Five Fit Together Path One: Building a Self-Managed Open Lakehouse Path Two: