What is Polaris Catalog?
Apache Polaris (originally released as Polaris Catalog) is an open-source catalog for Apache Iceberg tables that implements the Iceberg REST Catalog specification.
Polaris Catalog was open-sourced by Snowflake in 2024 and entered the Apache Incubator that August, with Dremio, Snowflake, and other companies contributing. It graduated to an Apache Top-Level Project in February 2026. Because it speaks the standard Iceberg REST protocol, engines such as Spark, Flink, Trino, Dremio, and Snowflake can all use the same Polaris catalog to find and commit to Iceberg tables.
Core Architecture and Mechanics
Polaris has a few core responsibilities:
- Tracks the current metadata location for each Iceberg table. Commits go through the catalog, which updates that pointer atomically so Iceberg transactions stay consistent across engines.
- Organizes tables into catalogs and namespaces. A single Polaris deployment can host multiple catalogs, each tied to its own storage location in S3, Azure Storage, or Google Cloud Storage.
- Enforces role-based access control and vends credentials. Principals receive roles that grant privileges on catalogs, namespaces, and tables, and Polaris can issue short-lived storage credentials scoped to the tables an engine is allowed to access.
Because it follows the open REST specification, any Iceberg client that supports REST catalogs can connect to Polaris without a custom integration.
Why Polaris Catalog Matters in the Modern Data Stack
A lakehouse is only as open as its catalog. If tables are registered in a catalog that only one engine can use, the open table format does little to reduce lock-in. Polaris gives multiple engines a shared, vendor-neutral catalog, so they can work on the same tables without copying data.
For organizations with many teams and tools, Polaris centralizes table discovery and access rules in one place instead of configuring them separately in each engine. Managed services based on Polaris are also available, for example from Snowflake and Dremio.
Key Benefits
- Interoperability: One catalog for many Iceberg engines through the REST protocol.
- Vendor Neutrality: An Apache Software Foundation project governed by a multi-company community.
- Centralized Security: Role-based access control and credential vending managed in the catalog.
Frequently Asked Questions
What makes a Lakehouse different from a Data Lake?
A standard data lake is just a collection of files. A lakehouse adds a metadata layer that provides warehouse-like features (transactions, schema enforcement) directly to those files. The catalog, such as Polaris, is the piece that tells every engine which tables exist and where their current metadata lives.
Why use an Open Table Format?
Open formats like Apache Iceberg keep your data readable by many engines instead of one proprietary database. Pairing an open format with an open catalog like Polaris extends that openness to table discovery and access control.
How does Polaris Catalog impact data governance and security?
Polaris applies role-based access control at the catalog level, so the same privileges apply no matter which engine connects. Credential vending means engines do not need long-lived storage keys for every bucket.
Learn More
To learn more about the Data Lakehouse, read The Lakehouse Built for Everyone by Alex Merced. You can find this and other books by Alex Merced at books.alexmerced.com.