Isolation Levels

A transaction read the status of Ana's booking twice, a moment apart, and received two different answers: CONFIRMED the first time and CANCELED the second. The transaction itself changed nothing. Between its two reads, another transaction canceled the booking and committed.

We then repeated the same steps with one setting changed on the reading transaction. This time both reads returned CONFIRMED, even though the cancellation had committed in exactly the same place.

The setting was the isolation level