Large Excel file as Knowledge source

Hi @Mayank Gupta, Vodafone,

According to your concern, refer to Quotas and limits - Microsoft Copilot Studio | Microsoft Learn, Microsoft Copilot Studio limits focus on file sizes, counts and source types, not row limits. However, from practical experience and community sharing, Excel seems to be not a first-class unstructured source. Based on Copilot Studio: Using Structured Data in Excel as SharePoint Knowledge Source, the same tabular content indexes more reliably when embedded in Word or PDF. The author did a side-by-side tests, Copilot Studio often retrieves from the DOCX/PDF copy but not from the Excel copy even though both are in the same SharePoint folder.

Therefore, the suggested practical approach for your situation will be:

1/ Treat the data as structured and fetch rows via a Tool/Action.

Instead of relying on indexing of the .xlsx, expose the table through an Excel Online connector or an agent flow that reads rows based on the user’s query (with filters, pagination). This bypasses the RAG index and queries the sheet directly at runtime.

2/ Convert the Excel table to a document people can cite (DOCX/PDF) and use it as knowledge.

If your use case is “answer policy/lookup questions from a table,” export the relevant table(s) to DOCX or PDF and store those in the same library. As I mentioned from the community sharing above, retrieval is much better from DOCX/PDF compared to xlsx. You can also keep the documents reasonably sized (split by category or letter range) and a simple layout (no merged cells, minimal images).

Hope this information may help. If you have any questions or need further assistance, please feel free to reach out in the comments under this post. I will be happy to assist you further.

Thank you for your understanding and cooperation. I'm looking forward to your response.

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