All systems I have worked on like this has some concept of a version number for each entity / aggregate.
So you get that the account_balance was 100$ on version 10 of the account, and write an event that deducts 10$ on version 11.
If another writer did the same at exact same time, they would write an event to deduct 100$ at version 11. There will be a conflict and only one version will win.
This is exactly like any optimistic concurrency control also without event as the primary storage.
Didn't check if the system linked to supports this, I guess it might not? But this primitive seems quite crucial to me.
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All systems I have worked on like this has some concept of a version number for each entity / aggregate.
So you get that the account_balance was 100$ on version 10 of the account, and write an event that deducts 10$ on version 11.
If another writer did the same at exact same time, they would write an event to deduct 100$ at version 11. There will be a conflict and only one version will win.
This is exactly like any optimistic concurrency control also without event as the primary storage.
Didn't check if the system linked to supports this, I guess it might not? But this primitive seems quite crucial to me.