Backend & systems·Transactions and isolation
you read the row at the start of the transaction, read it again at the end, and it has a different value because somebody committed in between.
Non-repeatable read
Also calledfuzzy read
The same row returning different values within one transaction. It is permitted at read committed and prevented at repeatable read. It bites in report generation and in any multi-step calculation, where two halves of the same answer are computed against different states of the world.