# Apache Polaris

[Apache Polaris](https://polaris.apache.org/) is an open-source Iceberg REST catalog. Connect it to Altertable when Polaris manages your Iceberg table metadata and you want to query those tables alongside the rest of your lakehouse.

## Connect Apache Polaris

1. Open **Catalogs** in the Altertable app.
2. Click **New catalog**.
3. Select **Apache Polaris**.
4. Enter the catalog URI, such as `https://polaris.example.com/api/catalog`, the warehouse (the name of the Polaris catalog), and the default namespace for unqualified table names. Tables in other namespaces stay queryable.
5. Choose an authentication method and enter its credentials.
6. Save the catalog, then query the Iceberg tables with SQL.

## Authentication

- **Client credentials**: the client ID and client secret of a Polaris principal. Altertable requests tokens from `<catalog URI>/v1/oauth/tokens` with the `PRINCIPAL_ROLE:ALL` scope unless you set a different token endpoint or scope.
- **Bearer token**: a static access token. Altertable sends it as is, so replace it in the catalog settings before it expires.

Altertable reads table data with the storage credentials Polaris vends for each table, so the catalog must have credential vending configured. Grant the principal role only the catalog privileges Altertable needs, such as `TABLE_READ_DATA` for read-only access.