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An external data source is a reusable, named connection that lets Transformations read from storage outside Cognite Data Fusion (CDF). For example, you can read Microsoft Fabric OneLake without staging a full copy in CDF RAW. Configure credentials and location once, then reference the source in transformation SQL by externalId. This API is enabled per project. If requests return that the endpoint isn’t enabled, contact Cognite Support.

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Concepts

  • Source type — The external system the source connects to. The supported value is one_lake for Microsoft Fabric OneLake.
  • Credentials — Microsoft Entra ID application credentials: clientId, tenantId, and clientSecret. The client secret is write-only; it is stored encrypted and never returned when you read a data source.
  • Location — Where in OneLake the source points: workspaceId and containerId, both as GUIDs.
  • Data set scoping — Optional dataSetId that scopes access to the data source through CDF data set permissions.

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Usability checks

Before you use an external data source in a transformation, call the usability endpoint (POST /transformations/externaldata/usability) to verify that CDF can reach the storage location with the stored credentials. The response reports whether the connection and permissions succeed, so you can fix configuration issues before a transformation job fails.

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Key capabilities

  • List external data sources configured for the project
  • Create external data sources with a unique externalId
  • Delete external data sources by id or externalId
  • Verify usability of a data source before using it in a transformation
If the externalId already exists in the project, POST /transformations/externaldata returns 409 and creates no items. To change a source, delete it and create a replacement. There is no update operation.
The stable (20230101) API reference does not include external data sources. Use the beta or alpha API reference for concepts and endpoint documentation. Send Cdf-Version: beta on requests. For how preview APIs relate to stable, see Beta API reference.

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Rate and concurrency limits

External data source operations share the general CDF request budgets. For limit types and throttling behavior, see API rate limits.
Last modified on August 28, 2026