Our orders are delivered strictly on time without delay
Our orders are delivered strictly on time without delay
There are times when a database is accessed by many users across the enterprise. Transaction logs can help maintain concurrency in a multiuser platform.
Describe at least two business scenarios where "commit" and "rollback" would be required.
Describe how these functions would be essential for business continuity and concurrency control.
Identify how these functions would enable an organization to recover from a database corruption event.
"Commit" and "rollback" are essential database functions that ensure data integrity, especially in a multiuser environment. They work within a transaction, which is a single, logical unit of work.
Scenario 1: Financial Transactions
A classic example is a money transfer between two bank accounts. The transaction involves two distinct operations:
Debit: Subtracting a specific amount from Account A.
Credit: Adding the same amount to Account B.
If only the debit operation succeeds but the credit fails (e.g., due to a system crash, network error, or invalid account number), the database would be left in an inconsistent state, with money debited from one account but not credited to the other.
Commit: If both the debit and credit operations are successful, the transaction is committed. This makes the changes permanent, and they can no longer be undone. The new balances for both accounts are now saved in the database.
Rollback: If any part of the transaction fails, a rollback is required. The database undoes all changes made within that transaction, reverting both accounts to their original state before the transfer began. This ensures that no money is lost and the database remains consistent.
Scenario 2: Inventory Management
Consider an e-commerce platform where a customer places an order for a product. The transaction involves several steps:
Order Creation: A new order record is created in the database.
Inventory Update: The quantity of the purchased item is decremented in the inventory table.
Payment Processing: The customer's credit card is charged.
If the inventory update is successful but the payment processing fails, the system must not finalize the order.
Commit: If the order is created, inventory is updated, and payment is successful, the transaction is committed, finalizing the sale. The order is now ready for fulfillment.
Rollback: If the payment processing fails for any reason, a rollback is performed. The order record is deleted, and the inventory count is restored to its original value. This prevents the company from selling an item that was never paid for and ensures the inventory is accurate.
Business Continuity: These functions are vital for business continuity because they guarantee that data remains reliable and accurate, even in the face of unexpected failures. By ensuring that transactions are either fully completed or completely undone, they prevent inconsistent or corrupt data from being written to the database. This allows the business to recover quickly and maintain operational integrity, as the data can be trusted. Without them, a single error could cascade and compromise the entire database, leading to service outages and significant financial losses.
Concurrency Control: In a multiuser environment, multiple transactions can try to access and modify the same data simultaneously. Concurrency control manages these interactions to prevent data inconsistencies. Commit and rollback are central to this. For example, if two customers try to buy the last remaining item at the same time, the database's locking mechanism will ensure that one transaction proceeds first. The second transaction will be forced to wait. Once the first transaction is committed, the second one can proceed. If the first transaction's inventory update fails and it has to rollback, the item becomes available again, allowing the second transaction to proceed successfully. This prevents over-selling and ensures data is handled sequentially and correctly.