Missing documentation: PATCH replaces chunks + 1MB gateway limit blocks large document ingestion

[ni-dz]

Issue description

Description:

While working with the Vector API for larger-scale ingestion, I encountered behavior that is currently not clearly documented and may lead to confusion during implementation.

It would be great if this could be clarified in the documentation to improve usability and developer experience.

Observed issues:

• There appears to be a ~1MB request size limit (API gateway), which results in 413 Payload Too Large errors for larger uploads.
• The PATCH /documents endpoint replaces existing chunks instead of appending them, making incremental uploads to a single document impossible.

Why this is confusing:

• The documentation states a limit of 200,000 chunks per document, which suggests that incremental ingestion should be supported.
• The PATCH endpoint is described as updating chunks, but it is not clearly stated that existing chunks are fully overwritten.
• The gateway request size limitation is not mentioned in the documentation.

Current workaround:

• Splitting data into multiple documents (or collections)
• Using metadata or collection-based filters during retrieval

Suggested improvements:

• Document the ~1MB request size limit and its implications
• Clarify that PATCH replaces chunks and does not support appending
• Provide recommended ingestion patterns / best practices for large datasets
• Clarify how the 200k chunk limit can realistically be achieved (e.g., via Pipeline API, if applicable)

Affected pages:

• Update a Document
• Vector API

Feedback Type (Optional)

content gaps

Page Title on SAP Help Portal (prefilled)

Update a Document

Page URL on SAP Help Portal (prefilled)

https://help.sap.com/docs/sap-ai-core/generative-ai/update-document-adaa7cc44d334d89baf1ef666ac3158c?locale=en-US

[karu-0711]

Hi @ni-dz . Thank you for your feedback! We’ll look into it and come back to you if we have any questions.

[Niveth-T]

@ni-dz Thankyou for your contribution.

We have updated the content and will be published in the near future.

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