in the explorer -> 'Global Writes' tab: compound shard key should support unique index property
set the compound index created during the Global Cluster configuration to be set as unique
today there is no option for that and it's a very basic need for those who using global clusters.
This is a timely piece of feedback as we have been working behind the scenes to make this possible! I’d like to share some good news: Atlas now allows you to use a unique index as the shard key of a global writes collection. This capability allows you to enforce a unique constraint on the entire shard key combination. See https://docs.atlas.mongodb.com/data-explorer/global-writes/#procedure for more details.