Does an Azure Content Understanding analyzer still use its labelled examples after the training container SAS expires?

Question

Does an Azure Content Understanding analyzer still use its labelled examples after the training container SAS expires?

Tim Atkins 0

Question

We’re using Azure Content Understanding API 2025-11-01 (GA) to build a custom document analyzer. During the build, we supply a Blob container SAS URL in knowledgeSources with kind: "labeledData".

The build succeeds, then the training SAS expires. We subsequently submit a new document as bytes to the same analyzer ID, without rebuilding it. The training SAS was the analyzer’s only means of accessing the original container.

Will the analyzer continue using its retained labelled examples in this scenario, or does it need to read the original blobs again during analysis?

Microsoft’s documentation says the built analyzer retains the labelled training data and uses it at analysis time. We’re trying to establish whether our production deployment can generate a short-lived SAS for each build and safely let it expire afterwards. Microsoft Learn – labelled data for custom analyzers

If ongoing Blob access is required, would an expired SAS cause an explicit error, or could analysis succeed without using the examples? A reference confirming the supported behaviour for the GA API would be appreciated.

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Answer 1

Hello @Tim Atkins

For API version 2025-11-01, a built analyzer retains the labeled training data and uses it during analysis. Therefore, after the analyzer build has completed successfully, normal analysis requests shouldn’t need to read the original Blob container again. The Analyze API receives the analyzer ID and the new document input; it doesn’t require the training-container URL.

Based on that documented lifecycle, you can use a short-lived SAS for the build, provided it remains valid until the asynchronous build operation reaches Succeeded. Expiration afterward shouldn’t prevent that already-built analyzer from using its retained labeled data.

A new valid SAS would be required whenever the service must access the source data again, for example, when updating the labeled samples and rebuilding the analyzer. Microsoft’s customization guidance requires rebuilding after labeled samples are added or changed.

Microsoft doesn’t document a mode in which a successfully built 2025-11-01 analyzer silently stops using its retained examples because the original SAS expired.

References:

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