What methods can be used to test a database that does not support transactions?

If the database does not support transactions, verifying its operation and data integrity requires other approaches:

• Idempotency of operations: design operations so that repeated execution does not lead to errors or inconsistent data.
• Integrity checks at the application level: implement logic for data validation and recovery in the code, for example, through validation and compensatory actions.
• Logging changes: keep a change log to track the sequence of operations and enable manual rollback.
• Testing with failure simulation: create scenarios where operations are interrupted to test how the system recovers.
• Using external locking mechanisms or semaphores to prevent conflicts during concurrent access.

Example in Python for checking idempotency of a record:

class SimpleDB:
    def __init__(self):
        self.data = {}

    def write(self, key, value):
        if self.data.get(key) == value:
            return "No change needed"
        self.data[key] = value
        return "Value updated"

# Usage
db = SimpleDB()
print(db.write('user1', 'data1'))  # Value updated
print(db.write('user1', 'data1'))  # No change needed

Thus, control and verification are the responsibility of the application level and architecture, not built-in DBMS mechanisms.