quescol Multi-version protocol minimizes the delay for reading operation and maintains different versions of data items. For each writes operation performed, it creates a new version of transaction data so that whenever any transaction performs read operation to read that data then the appropriate created data version is selected by the control manager to make that … Read more
The optimistic control protocol is also called validation-based protocol which copies the transaction data locally and updates the local copy of data instead of actual data in the database. Optimistic Concurrency Control, or OCC, is like playing a game where you assume everything will go smoothly until you reach the end. Instead of checking every move, … Read more
Timestamp ordering is a unique value given to every transaction whenever it comes into the system to execute. There are two types of timestamp values Read timestamp: It is the value of the last transaction which successfully performed the read operation. Write timestamp: It is the value of the last transaction which successfully performed the … Read more
What is Strict 2 phase locking? Strict Two-Phase Locking (Strict 2PL) is a rule used in databases to keep information safe when many people are using it at the same time. It works in two main steps: The strict part means that all write locks (locks put on data that was changed) stay until the … Read more
The locking technique uses a lock that guarantees the exclusive use of data of transactions. The lock is used to restrict different transaction which is executing at the same time. 2-phase locking technique It is the same as the Locking technique explained above but it has two phases to act which are: Growing phase: It is … Read more
The locking technique uses a lock that guarantees the exclusive use of data of transactions. The lock is used to restrict different transaction which is executing at the same time. There are 3 phases of Locking technique Taking the lock control and accessing the data of the transaction Complete the transaction execution Release lock There … Read more
The concurrency control technique is a process of managing the simultaneous execution of transactions in a shared database. However, when the concurrent transaction techniques are executed in an uncontrolled manner then it leads to several problems. The five leading problems that occur due to uncontrolled execution of concurrent transactions are 1. Lost Update Problem 2. … Read more
Lost update and dirty read problem both are issues that appear due to uncontrolled execution of the concurrent transaction. Lost Update Problem A lost update problem appears when at least two transactions access the same transaction data and performs their operation. As we know, the data of transaction if the first read by the system … Read more
Imagine a busy kitchen where many cooks are preparing different dishes at the same time. They need to share ingredients, utensils, and cooking stations without getting in each other’s way. This is a bit like what happens in a computer database, where concurrency control is the rulebook that helps everyone work together smoothly. We need … Read more
Atomicity It states that a transaction must be treated as a single atomic unit i.e. Either transaction executed successfully or completely failed. It should not stuck in between or execute partially. The states of the transaction should be defined before execution or after the execution or failure or abortion of the transaction. For example: Suppose … Read more