What methods can be used to ensure the isolation of transactional operations in a database?

Transaction isolation in a database is achieved through isolation levels that control the visibility of changes between transactions. The main methods are:

• Read Uncommitted — the lowest isolation level, allows reading uncommitted data (dirty read).
• Read Committed — allows reading only committed data, preventing dirty reads.
• Repeatable Read — guarantees that data read in a transaction will not change until the transaction completes.
• Serializable — the strictest isolation level, ensures full transaction serializability.

In Python, transaction management is often handled using ORM (e.g., SQLAlchemy), where you can explicitly set the isolation level when opening a session or transaction:

from sqlalchemy import create_engine
engine = create_engine('postgresql://user:pass@localhost/db')

with engine.connect() as connection:
    trans = connection.begin()
    connection.execution_options(isolation_level="SERIALIZABLE")
    try:
        # database operations
        trans.commit()
    except:
        trans.rollback()
        raise

You can also use locks and optimistic concurrency for additional isolation.