> ## Documentation Index > Fetch the complete documentation index at: https://docs.startree.ai/llms.txt > Use this file to discover all available pages before exploring further. # Apache Polaris & Snowflake Open Catalog: Onboarding via API > Onboard an Apache Polaris or Snowflake Open Catalog Iceberg table as a StarTree External Table over the Iceberg REST API, authenticating with OAuth2 principal (client-id/client-secret) credentials. This feature requires StarTree release 0.16.0 or later, and must be enabled on demand — contact StarTree support to activate it. This page shows how to onboard an **Apache Polaris** or **Snowflake Open Catalog** External Table with the StarTree controller REST APIs. There is no Data Portal wizard for these yet — this API flow is the only way to onboard one today. Polaris tables are accessed over the standard **Iceberg REST protocol**. There's no dedicated `serviceType` for Polaris — use the generic spec-compliant adapter: `catalogType=iceberg-rest`, `serviceType=rest`, with `catalog.iceberg-rest.warehouse` set to the Polaris **catalog name**. Data files must be **Parquet**. > Using **Nessie**? It rides the same generic `rest` adapter with a branch/ref `prefix` — see [Nessie: Onboarding via API](../nessie/onboarding-api). ## Apache Polaris and Snowflake Open Catalog **Snowflake Open Catalog** is Snowflake's managed Apache Polaris service. It speaks the same Iceberg REST protocol and uses the same **principal**-based OAuth2 (`client-id` / `client-secret`, `PRINCIPAL_ROLE:ALL` scope) as self-managed Polaris — only the host and token-endpoint path differ. Self-managed Polaris serves the REST API under `/api/catalog`; Open Catalog serves it under `https://-.snowflakecomputing.com/polaris/api/catalog`. Everything else on this page — principal credentials, scope, catalog-name `warehouse` — applies to both. Using **Snowflake Horizon Catalog** instead? Snowflake has stopped provisioning new Open Catalog accounts and now routes customers to **Horizon**, which exposes the same Polaris REST API on the Snowflake account host but authenticates differently (a service-user **PAT** passed as the catalog credential, a `session:role:` scope, and a required `prefix`). It has its own page: [Snowflake Horizon Catalog: Onboarding via API](../horizon/onboarding-api). ## How it works Onboarding is four calls. Each one feeds the next: ```text theme={null} 1. Validate & browse POST /connections/browse → validate; list namespaces/tables 2. Preview POST /tables/preview → infer schema + enriched table config 3. Create schema POST /schemas → register the schema 4. Create table POST /tables → register the External Table ``` The preview call (step 2) is the core step: it samples the source, infers a Pinot schema, and returns a ready-to-use table config. Steps 3 and 4 just persist its output. Once the table exists, the controller's watcher runs the first sync and re-syncs on schedule — no manual trigger. Track progress with the [observability endpoints](#monitor-onboarding). All paths are relative to your data-plane base URL. Set `export BASE_URL=https://dp..cp..startree.cloud/api/pinot` (the StarTree Cloud data-plane proxy). A browse call then posts to `$BASE_URL/connections/browse`. If your controller requires authentication, add an `Authorization` header to every request — e.g. `-H "Authorization: Bearer "`. The examples below omit it for brevity. ## Prerequisites * StarTree 0.16.0 or later with the External Table Beta feature enabled, and **tiered storage configured** on the cluster. Contact StarTree support if unsure. * Network access to the controller REST endpoint, plus an `Authorization` token if your cluster requires auth. * A running Polaris deployment with its Iceberg REST API reachable: self-managed Apache Polaris serves it under `/api/catalog`; Snowflake Open Catalog serves it under `https://-.snowflakecomputing.com/polaris/api/catalog`. * A Polaris **principal** with client credentials (`client-id` / `client-secret`) whose principal role maps, through a catalog role, to at least read grants on the target catalog (for example `TABLE_READ_DATA`, which implies the list/metadata grants needed for browsing). See the [Polaris access-control docs](https://polaris.apache.org/) for creating principals, principal roles, catalog roles, and grants. * The Polaris **catalog name** (used as the `warehouse`) and the namespace/table to onboard. * Read access to the underlying object storage. This connector supports **S3-compatible storage** for the data files. ## Limitations * **No credential vending.** Polaris can vend short-lived storage credentials to engines that request them, but the generic `rest` adapter does not consume vended credentials — configure static keys, an assumed role, or the cluster's node role for storage explicitly. ## Authentication An External Table authenticates in two places, configured independently: * **Catalog (REST)** — keys under `catalog.iceberg-rest.auth.rest.*`. Polaris always requires authentication; choose one of the methods below. * **Storage (S3 data files)** — keys under `catalog.iceberg-rest.auth.storage.*`. Choose one of the three methods below. ### Catalog (REST) authentication: choose one #### OAuth2 client credentials (recommended) The standard Polaris method: the principal's `client-id` / `client-secret` are exchanged at the Polaris token endpoint for a short-lived token, which StarTree caches and refreshes automatically. `authType` is optional; it's auto-detected as `oauth2` once the three required keys below are all present. Polaris requires a scope naming the principal role to activate — use `PRINCIPAL_ROLE:ALL` to activate all of the principal's roles, or `PRINCIPAL_ROLE:` to restrict the session to one role. ```json theme={null} { "catalog.iceberg-rest.auth.rest.authType": "oauth2", "catalog.iceberg-rest.auth.rest.oauthTokenUri": "https:///api/catalog/v1/oauth/tokens", "catalog.iceberg-rest.auth.rest.oauthClientId": "", "catalog.iceberg-rest.auth.rest.oauthClientSecret": "", "catalog.iceberg-rest.auth.rest.oauthScopes": "PRINCIPAL_ROLE:ALL" } ``` For **Snowflake Open Catalog**, the token endpoint is the same path on the account host: `https://-.snowflakecomputing.com/polaris/api/catalog/v1/oauth/tokens`. #### OAuth2 against an external identity provider Polaris deployments configured to trust an external IdP (Keycloak, Okta, and so on) accept tokens minted by that IdP instead of the built-in token endpoint. Use the same four keys, pointing `oauthTokenUri` at the IdP's client-credentials token endpoint and setting whatever scopes the IdP requires. ```json theme={null} { "catalog.iceberg-rest.auth.rest.authType": "oauth2", "catalog.iceberg-rest.auth.rest.oauthTokenUri": "https:///realms//protocol/openid-connect/token", "catalog.iceberg-rest.auth.rest.oauthClientId": "", "catalog.iceberg-rest.auth.rest.oauthClientSecret": "", "catalog.iceberg-rest.auth.rest.oauthScopes": "" } ``` #### Bearer token If you already hold a valid token (for example, minted out-of-band from your IdP), pass it directly. `authType` doesn't need to be set explicitly — it's auto-detected as token auth when `.token` is present. Note that a static token is **not refreshed**: when it expires, syncs start failing until the table config is updated, so prefer the OAuth2 client-credentials flow for anything long-running. ```json theme={null} { "catalog.iceberg-rest.auth.rest.token": "" } ``` ### Storage authentication: choose one #### Assumed IAM role (recommended for production) No static secrets in the table config — every S3 read assumes `roleArn` via STS. ```json theme={null} { "catalog.iceberg-rest.auth.storage.roleArn": "arn:aws:iam::123456789012:role/pinot-external-table-reader", "catalog.iceberg-rest.auth.storage.externalId": "", "catalog.iceberg-rest.auth.storage.region": "" } ``` #### Cluster node role Omit every `auth.storage.*` credential key — only `region` is required. Credential resolution falls back to the AWS SDK default chain (the node's instance profile / IRSA role), which must already have S3 access. ```json theme={null} { "catalog.iceberg-rest.auth.storage.region": "" } ``` #### Static access keys Quick tests, or when role-based access isn't available. Accepts either `accessKeyId`/`secretAccessKey` or the shorter `accessKey`/`secretKey` aliases. ```json theme={null} { "catalog.iceberg-rest.auth.storage.accessKeyId": "", "catalog.iceberg-rest.auth.storage.secretAccessKey": "", "catalog.iceberg-rest.auth.storage.region": "" } ``` ### Selecting the catalog A Polaris server hosts multiple catalogs. Set `catalog.iceberg-rest.warehouse` to the catalog name — the adapter passes it to the server's config endpoint, which resolves the per-catalog prefix automatically. ```json theme={null} { "catalog.iceberg-rest.warehouse": "", "catalog.iceberg-rest.prefix": "" } ``` Also set `catalog.iceberg-rest.prefix` to the catalog name whenever the prefix can't be negotiated automatically. This is **required for Snowflake Open Catalog** and any deployment whose `/v1/config` endpoint gates on the `warehouse` query parameter, or that sits behind a proxy which doesn't forward the config handshake. Without it, browse fails with `404 Unable to find matching target resource method`, because the request falls back to the un-prefixed `/v1/namespaces` path. The examples below set both `warehouse` and `prefix`. *** ## Step 1: Validate and browse the connection **`POST /connections/browse`** There is no separate "validate" endpoint. Browsing the catalog *is* the validation step: a `200` with an `items` list (even an empty one) confirms your credentials, scope, and connectivity. * Set `path` to `""` to browse the **root** — this both validates the connection and lists namespaces. * Set `path` to a namespace name to list the **tables** inside it. ### Request | Field | Type | Required | Description | | ------------------- | ------ | -------- | ------------------------------------------------------------------------------------ | | `connection.type` | string | Yes | Use `CATALOG` for all External Table sources. | | `connection.params` | object | Yes | Catalog-specific connection settings (see example below). | | `path` | string | No | Where to browse. `""` or omitted = root. A namespace name = that namespace's tables. | ```bash theme={null} curl -X POST "$BASE_URL/connections/browse" \ -H "Content-Type: application/json" \ -d '{ "connection": { "type": "CATALOG", "params": { "catalogType": "iceberg-rest", "catalog.iceberg-rest.serviceType": "rest", "catalog.iceberg-rest.restUri": "https:///api/catalog", "catalog.iceberg-rest.warehouse": "", "catalog.iceberg-rest.prefix": "", "catalog.iceberg-rest.auth.rest.authType": "oauth2", "catalog.iceberg-rest.auth.rest.oauthTokenUri": "https:///api/catalog/v1/oauth/tokens", "catalog.iceberg-rest.auth.rest.oauthClientId": "", "catalog.iceberg-rest.auth.rest.oauthClientSecret": "", "catalog.iceberg-rest.auth.rest.oauthScopes": "PRINCIPAL_ROLE:ALL", "catalog.iceberg-rest.auth.storage.roleArn": "arn:aws:iam::123456789012:role/pinot-external-table-reader", "catalog.iceberg-rest.auth.storage.externalId": "", "catalog.iceberg-rest.auth.storage.region": "" } }, "path": "" }' ``` | Key | Value | Description | | ---------------------------------- | ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------ | | `catalog.iceberg-rest.restUri` | `https:///api/catalog` | The Polaris Iceberg REST base URI (Snowflake Open Catalog: `https://-.snowflakecomputing.com/polaris/api/catalog`). | | `catalog.iceberg-rest.serviceType` | `rest` | Selects the generic spec-compliant adapter — there's no Polaris-specific `serviceType`. | | `catalog.iceberg-rest.warehouse` | `` | The Polaris catalog to browse; the server resolves the per-catalog prefix from it. | | `catalog.iceberg-rest.prefix` | `` | Pins the catalog prefix explicitly. Required for Snowflake Open Catalog and any proxy that doesn't forward the config handshake. | ### Response ```json theme={null} { "items": [ { "name": "transportation", "type": "NAMESPACE" }, { "name": "nyc_taxi_trips", "type": "TABLE" } ] } ``` | `items[].type` | Meaning | | -------------- | ----------------------------------------------------------- | | `NAMESPACE` | A namespace you can drill into — pass its `name` as `path`. | | `TABLE` | A selectable table. | *** ## Step 2: Preview the schema **`POST /tables/preview`** Samples the source, infers a Pinot schema, and returns an enriched table config (S3 tier, raw field configs, time column) plus sample rows. Review it, tweak if needed, then carry the schema and config forward to steps 3 and 4. The request and response share the same JSON shape. You send a `tableConfig` describing the source; the response fills in `schema`, the enriched `tableConfigs.offline`, sampled `rows`, and a `summary`. ### Request **Top-level fields:** | Field | Type | Required | Description | | ------------- | ------ | -------- | --------------------------------------------------------------------------------------- | | `tableConfig` | object | Yes | A single OFFLINE table config whose `ExternalTableSyncTask` block describes the source. | | `config` | object | No | Sampling and inference controls (see below). Defaults are applied if omitted. | | `schema` | object | No | An explicit schema to use instead of inferring one. | **`config.inference` — how the schema is derived:** | Field | Type | Default | Description | | ------------------------ | ------- | ------- | --------------------------------------------------------------------------------------------- | | `embeddedSchemaEnabled` | boolean | `false` | Read the schema embedded in the Iceberg metadata. **Set this to `true` for External Tables.** | | `schemaInferenceEnabled` | boolean | `false` | Infer the schema from sampled rows. Fallback when no embedded schema exists. | Resolution order: explicit `schema` → embedded schema → inferred schema. **`config.sampling` — how rows are sampled:** | Field | Type | Default | Description | | ----- | ------- | ------- | -------------------------- | | `min` | integer | `1` | Minimum records to sample. | | `max` | integer | `100` | Maximum records to sample. | ```bash theme={null} curl -X POST "$BASE_URL/tables/preview" \ -H "Content-Type: application/json" \ -d '{ "tableConfig": { "tableName": "nyc_taxi_trips_OFFLINE", "tableType": "OFFLINE", "task": { "taskTypeConfigsMap": { "ExternalTableSyncTask": { "catalogType": "iceberg-rest", "executor": "controller", "inputFormat": "parquet", "catalog.iceberg-rest.serviceType": "rest", "catalog.iceberg-rest.restUri": "https:///api/catalog", "catalog.iceberg-rest.warehouse": "", "catalog.iceberg-rest.prefix": "", "catalog.iceberg-rest.table.namespace": "transportation", "catalog.iceberg-rest.table.tableName": "nyc_taxi_trips", "catalog.iceberg-rest.auth.rest.authType": "oauth2", "catalog.iceberg-rest.auth.rest.oauthTokenUri": "https:///api/catalog/v1/oauth/tokens", "catalog.iceberg-rest.auth.rest.oauthClientId": "", "catalog.iceberg-rest.auth.rest.oauthClientSecret": "", "catalog.iceberg-rest.auth.rest.oauthScopes": "PRINCIPAL_ROLE:ALL", "catalog.iceberg-rest.auth.storage.roleArn": "arn:aws:iam::123456789012:role/pinot-external-table-reader", "catalog.iceberg-rest.auth.storage.externalId": "", "catalog.iceberg-rest.auth.storage.region": "" } } } }, "config": { "inference": { "embeddedSchemaEnabled": true } } }' ``` **Setting the namespace and table.** Take them from the [browse](#step-1-validate-and-browse-the-connection) response — set `catalog.iceberg-rest.table.namespace` / `.tableName` to the `NAMESPACE` and `TABLE` you selected. **Use `executor: controller`** — it's required for the controller-watcher flow and the [observability endpoints](../observability). The input `tableConfig` is intentionally minimal; `/tables/preview` returns the complete `tableConfigs.offline` you persist in Step 4. ### Response | Field | Type | Description | | ---------------------- | ------ | ----------------------------------------------------------------------------------------------------------- | | `schema` | object | The resolved Pinot schema. **Use this in step 3.** | | `tableConfigs.offline` | object | The enriched OFFLINE table config, ready to persist. **Use this in step 4.** Secrets are masked as `*****`. | | `rows` | array | Sample records after schema + ingestion transforms. | | `sourceRows` | array | Raw records before transformation. | | `summary` | object | Run summary: `nSourceRows`, `nRows`, `nColumns`, and `summary.batch.nMatchingFiles` (files found). | Adjust the schema (time column, column names, null handling) before moving on. *** ## Step 3: Create the schema **`POST /schemas`** Send the `schema` object from the preview response. Rename its `schemaName` to match your table. ```bash theme={null} curl -X POST "$BASE_URL/schemas" \ -H "Content-Type: application/json" \ -d @schema.json ``` ```json theme={null} { "status": "nyc_taxi_trips successfully added" } ``` *** ## Step 4: Create the table **`POST /tables`** Send the enriched `tableConfigs.offline` object from the preview response. Its `ExternalTableSyncTask` block is what marks the table as external. ```bash theme={null} curl -X POST "$BASE_URL/tables" \ -H "Content-Type: application/json" \ -d @tableConfig.json ``` ```json theme={null} { "status": "Table nyc_taxi_trips_OFFLINE successfully added" } ``` The controller's External Table watcher then discovers the table, runs the first sync, and re-syncs at the `schedule` (cron) interval. There is no separate start call. The first sync runs on the watcher's next tick. To kick it off immediately instead of waiting, you can manually trigger a run: ```bash theme={null} curl -X POST "$BASE_URL/tasks/schedule?taskType=ExternalTableSyncTask&tableName=nyc_taxi_trips_OFFLINE" ``` *** ## Quickstart: onboard a table end-to-end The whole flow as one script. Fill in the variables at the top, run the script, and the first sync starts automatically. ```bash theme={null} #!/usr/bin/env bash set -euo pipefail BASE_URL="https://dp..cp..startree.cloud/api/pinot" AUTH="Authorization: Bearer " REST_URI="https:///api/catalog" TOKEN_URI="https:///api/catalog/v1/oauth/tokens" WAREHOUSE="" PREFIX="" CLIENT_ID="" CLIENT_SECRET="" SCOPES="PRINCIPAL_ROLE:ALL" NAMESPACE="transportation" TABLE="nyc_taxi_trips" STORAGE_ROLE_ARN="arn:aws:iam::123456789012:role/pinot-external-table-reader" STORAGE_EXTERNAL_ID="" STORAGE_REGION="" # 1. Validate & browse root — lists namespaces in the Polaris catalog. curl -sf -X POST "$BASE_URL/connections/browse" \ -H "$AUTH" -H 'Content-Type: application/json' \ --data-raw "{ \"connection\": { \"type\": \"CATALOG\", \"params\": { \"catalogType\": \"iceberg-rest\", \"catalog.iceberg-rest.serviceType\": \"rest\", \"catalog.iceberg-rest.restUri\": \"$REST_URI\", \"catalog.iceberg-rest.warehouse\": \"$WAREHOUSE\", \"catalog.iceberg-rest.prefix\": \"$PREFIX\", \"catalog.iceberg-rest.auth.rest.authType\": \"oauth2\", \"catalog.iceberg-rest.auth.rest.oauthTokenUri\": \"$TOKEN_URI\", \"catalog.iceberg-rest.auth.rest.oauthClientId\": \"$CLIENT_ID\", \"catalog.iceberg-rest.auth.rest.oauthClientSecret\": \"$CLIENT_SECRET\", \"catalog.iceberg-rest.auth.rest.oauthScopes\": \"$SCOPES\" } }, \"path\": \"\" }" | jq . # 2. Preview — infer schema + enriched table config. curl -sf -X POST "$BASE_URL/tables/preview" \ -H "$AUTH" -H 'Content-Type: application/json' \ --data-raw "{ \"tableConfig\": { \"tableName\": \"${TABLE}_OFFLINE\", \"tableType\": \"OFFLINE\", \"task\": { \"taskTypeConfigsMap\": { \"ExternalTableSyncTask\": { \"catalogType\": \"iceberg-rest\", \"executor\": \"controller\", \"inputFormat\": \"parquet\", \"catalog.iceberg-rest.serviceType\": \"rest\", \"catalog.iceberg-rest.restUri\": \"$REST_URI\", \"catalog.iceberg-rest.warehouse\": \"$WAREHOUSE\", \"catalog.iceberg-rest.prefix\": \"$PREFIX\", \"catalog.iceberg-rest.table.namespace\": \"$NAMESPACE\", \"catalog.iceberg-rest.table.tableName\": \"$TABLE\", \"catalog.iceberg-rest.auth.rest.authType\": \"oauth2\", \"catalog.iceberg-rest.auth.rest.oauthTokenUri\": \"$TOKEN_URI\", \"catalog.iceberg-rest.auth.rest.oauthClientId\": \"$CLIENT_ID\", \"catalog.iceberg-rest.auth.rest.oauthClientSecret\": \"$CLIENT_SECRET\", \"catalog.iceberg-rest.auth.rest.oauthScopes\": \"$SCOPES\", \"catalog.iceberg-rest.auth.storage.roleArn\": \"$STORAGE_ROLE_ARN\", \"catalog.iceberg-rest.auth.storage.externalId\": \"$STORAGE_EXTERNAL_ID\", \"catalog.iceberg-rest.auth.storage.region\": \"$STORAGE_REGION\" } } } }, \"config\": { \"inference\": { \"embeddedSchemaEnabled\": true } } }" > preview.json # 3. Extract schema and table config from preview response. jq --arg t "$TABLE" '.schema | .schemaName = $t' preview.json > schema.json jq '.tableConfigs.offline' preview.json > tableConfig.json # 4. Create the schema. curl -sf -X POST "$BASE_URL/schemas" \ -H "$AUTH" -H 'Content-Type: application/json' -d @schema.json # 5. Create the table — watcher starts the first sync automatically. curl -sf -X POST "$BASE_URL/tables" \ -H "$AUTH" -H 'Content-Type: application/json' -d @tableConfig.json # 6. (optional) Poll until sync completes. curl -sf "$BASE_URL/tables/${TABLE}_OFFLINE/externalTable/status" -H "$AUTH" \ | jq -e '.status == "COMPLETED" and .segmentsUploaded == .filesDiscovered' ``` The script uses an assumed IAM role for storage (`auth.storage.roleArn`); swap in static keys or the node-role default (`region` only) from [Authentication](#authentication) if that fits your setup better. Once step 6 exits `0`, [verify it's queryable](#verify-its-queryable). ## Monitor onboarding The [status endpoint](../observability#run-status) reports each sync run's progress, and `?includeLag=true` adds how far the table trails the upstream catalog. Both require `executor=controller` (set automatically by this flow). See [Observability](../observability) for full request and response details. ## Verify it's queryable When `status` is `COMPLETED` and `segmentsUploaded` matches `filesDiscovered`, run a query against the broker (or the Data Portal query console) to confirm the data is live: ```sql theme={null} SELECT count(*) FROM nyc_taxi_trips; ``` The count will be much larger than the preview's `summary.nSourceRows` (preview only samples up to \~100 rows) — confirm it's non-zero and plausible for your dataset. If `status` is `COMPLETED` but the count is `0`, give segments a moment to load on the servers, then recheck; if it persists, see [Troubleshooting](../troubleshooting). *** ## What's next Now that the table is created and data is loading, these are the highest-impact follow-up steps: 1. **Add indexes for your query patterns.** Without indexes, every query scans all remote Parquet data. Add a range index on time/numeric columns, an inverted index on low-cardinality filter columns, and a bloom filter on high-cardinality ID columns. → [Indexes](../indexes) 2. **Enable caching and preload.** Set `enable.prefetch.page.cache=true` and `preload.enable=true` on the S3 tier so index data is served from local disk on repeated queries instead of re-fetched from S3. → [Data and Index Caching](../data-and-index-caching) 3. **Protect large-scan queries from OOM.** For tables that receive heavy aggregations or wide scans, enable the query OOM killer so a runaway query is killed instead of crashing the server. → [Best Practices & Configs — Query OOM protection](../best-practices-and-configs#query-oom-protection-large-scans) 4. **Monitor ongoing syncs.** Use the status endpoint (with `includeLag=true` for ingestion lag) after each scheduled sync. → [Observability](../observability) *** For common questions and failures, see the [FAQ](../faq) and [Troubleshooting](../troubleshooting).