Uniqueness and sql serialize

Hi fellow programmers,

I was looking for how to keep integrity in some financial transactions
I saw this “This could even happen if you use transactions with the
serializable isolation level.” in the uniqueness page
How this is possible with the serializablo isolation level? Aren’t the
select and update done in the same transaction?

On Wednesday, 24 October 2012 18:26:15 UTC-4, Filipe Giusti wrote:

They are, but that doesn’t prevent races like the one in the
from occurring - in that case, both transactions find no conflicting
records and create a row.

As noted in the docs, if you really really need data consistency you’re
better off using a unique index and catching

–Matt J.