在Google云端硬盘中部分编辑文档

This is a conceptual question regarding the realtime editing of large files. Imagine we have a 50 Mb txt file in Google Drive that we want to allow users to edit. We require that the user downloads the entire file before they start editing (The user will have to wait for a while, but this is ok). The user then changes a single word in the 50 Mb text file. How can we possibly update the file in Google Drive without uploading all 50 Mb of text.This is a conceptual question regarding the rea