A trading platform must have a 1:1 mapping of buyer to assets when trades are agreed. You cannot have a situation where two people buy the same share, as it requires unwinding. A trade must be atomic.
traders want to see all the bids/asks of the whole market. Otherwise you'll effectively have a random assortment of tiny markets under one supposedly united trading platform.
Thats the other thing, trades need to be reversible. There is a good correlation between massive trade volumes and the need to reverse transaction. Having an eventually consistent model is just not going to work.
Being overdrawn is not eventual consistency. The act of an overdraft is not a failure of a bank to properly account for your balance, its a deliberate business move to generate cash.
So no, its consistency, one price, one bid, one ask.
The concept of overdrafting is a combination of modern business rule and ancient technological limitation (dating back to before-computers when accounting was manual and checks and checkbooks were also big deal, which his hella-eventually consistent). It can still serve as a useful metaphor, regardless.
But if you care about operating the EXCHANGE ITSELF then your allusion to the audit trail is a bit of a red herring, isn't it? In fact, the data store itself becomes pretty irrelevant for the live trade-matching - presumably you shard just the hell out of your data, keep the working set in RAM, keep most of your stuff colocated in the same place and just solve for availability by doing something crazy and hardware-intensive like having hot spares for everything.
A trading platform must have a 1:1 mapping of buyer to assets when trades are agreed. You cannot have a situation where two people buy the same share, as it requires unwinding. A trade must be atomic.
traders want to see all the bids/asks of the whole market. Otherwise you'll effectively have a random assortment of tiny markets under one supposedly united trading platform.
Thats the other thing, trades need to be reversible. There is a good correlation between massive trade volumes and the need to reverse transaction. Having an eventually consistent model is just not going to work.
Being overdrawn is not eventual consistency. The act of an overdraft is not a failure of a bank to properly account for your balance, its a deliberate business move to generate cash.
So no, its consistency, one price, one bid, one ask.