What is the recommended minimum file size when working with external data on files in Microsoft Fabric?

• A. At least 10 MB.
• B. At least 1 MB.
• C. At least 4 MB.
• D. At least 5 MB.

Answer: (C)

In Fabric, how you size external data files affects how efficiently the system can read and parallelize work. Using at least four megabytes per file provides enough data per read so that metadata overhead doesn’t dominate and the engine can distribute work across nodes effectively. Small files (like much less than four MB) create a flood of metadata and scheduling tasks, hurting throughput. Very large files can reduce parallelism, whereas a practical minimum around four MB strikes a balance, giving good read performance with manageable metadata. That’s why four megabytes is the recommended minimum.