It may be rare in this context. But a common requirement in asset management is eg: account holder X has a regulatory constraint that they may only control 5% o

It may be rare in this context. But a common requirement in asset management is eg: account holder X has a regulatory constraint that they may only control 5% or less of securities in the ABC industry across all accounts. So all trades must be validated that they don’t cross this line. In real life, the account holder may decide to sell shares of one company from the ABC list from one account so they can buy other shares from the list in another account. The serializable isolation level does not guarantee reporting this correctly, and a concurrent process reading account balances could see a situation where account holder X is out-of-bounds of their regulatory constraints, despite the account holder themselves taking great pains to act lawfully. For applications like this, strict-serializability is required. You can read more about isolation levels and anomalies in the article from comp sci Professor Daniel Abadi: https://fauna.com/blog/introduction-to-transaction-isolation-levels https://fauna.com/blog/introduction-to-transaction-isolation...