Support Parallel Write Buffer for Azure Blob Storage

Why it matters

This feature improves the performance and efficiency of uploading data to Azure Blob Storage by allowing multiple parts to be uploaded in parallel. It helps reduce upload time and enhance throughput, which is especially beneficial for large data writes.

How to use it

Enable parallel write buffering by setting azure_allow_parallel_part_upload to 1 in the ClickHouse configuration or session settings when using Azure Blob Storage as the external storage backend.