Contents
- 1 When the transaction finishes the final statement the transaction enters into?
- 2 What is main mode in which a data item may be locked?
- 3 Is released when a transaction is completed so another transaction can lock the data item for its exclusive use?
- 4 Which of the following can cause a transaction failure?
- 5 What is two phase locking and how we can prevent deadlock?
- 6 What are the three 3 main problems in concurrency control?
- 7 When does a transaction acquire a data lock?
- 8 When is a transaction granted a lock in RDBMS?
- 9 What does it mean when a database is locked?
When the transaction finishes the final statement the transaction enters into?
Discussion Forum
| Que. | When the transaction finishes the final statement the transaction enters into |
|---|---|
| b. | Committed state |
| c. | Partially committed state |
| d. | Abort state |
| Answer:Partially committed state |
What is main mode in which a data item may be locked?
∎ A lock is a mechanism to control concurrent access to a data item ∎ Data items can be locked in two modes : 1. exclusive (X) mode. Data item can be both read as well as written.
What is lock point of the transaction?
The “Lock Point” is when all locks are held for the whole transaction. Binds all of the data used in a transaction together. It, therefore, prevents a transaction from being split into parts.
Is released when a transaction is completed so another transaction can lock the data item for its exclusive use?
A transaction acquires a lock prior to data access; the lock is released (unlocked) when the transaction is completed so that another transaction can lock the data item for its exclusive use.
Which of the following can cause a transaction failure?
Explanation: Logical errors and system errors are the two types of errors that can generally cause transaction failures.
Which of the following belongs to transaction failure?
Explanation: Types of system failure are transaction failure, system crash and disk failure. Explanation: Types of system transaction failure are logical and system error. The failure occurred sufficiently early during the transfer that the destination block remains intact.
What is two phase locking and how we can prevent deadlock?
Two phase locking prevents deadlock from occuring in distributed systems by releasing all the resources it has acquired, if it is not possible to obtain all the resources required without waiting for another process to finish using a lock. This means that deadlock cannot occur due to resource contention.
What are the three 3 main problems in concurrency control?
The concurrency control has the following three main problems:
- Lost updates.
- Dirty read (or uncommitted data).
- Unrepeatable read (or inconsistent retrievals).
Is used to solve the problems raised when two transactions are running concurrently?
The concurrency control protocols ensure the atomicity, consistency, isolation, durability and serializability of the concurrent execution of the database transactions. Therefore, these protocols are categorized as: Lock Based Concurrency Control Protocol.
When does a transaction acquire a data lock?
A transaction acquires a lock prior to data access. The lock is released (unlocked) when the transaction is completed so that another transaction can lock the data item for its exclusive use. Data consistency cannot be guaranteed during a transaction
When is a transaction granted a lock in RDBMS?
Explanation: If a transaction can be granted a lock on an item immediately in spite of the presence of another mode, then the two modes are said to be compatible. 5. A transaction is made to wait until all ________ locks held on the item are released
When does transaction T2 have access to data item?
In other words, transaction T2 does not have access to a data item that is currently being used by transaction T1. A transaction acquires a lock prior to data access. The lock is released (unlocked) when the transaction is completed so that another transaction can lock the data item for its exclusive use.
What does it mean when a database is locked?
In a database-level lock, the entire database is locked, thus preventing the use of any tables in the database by transaction T2 while transaction Tl is being executed. This level of locking is good for batch processes, but it is unsuitable for multiuser DBMSs.