Quickcomputerstips
A non recoverable schedule means: When there is a system failures, we may not be able to recover to a consistent database state.
- What is non-serial schedule in DBMS?
- Which are recoverable and Cascadeless schedules?
- What is a recoverable schedule is one where?
- What is serializable & non serializable schedule?
- What is non recoverable schedule?
- What is the mean of recoverable schedule?
- What do you mean by Cascadeless schedules?
- Which of the following is not a transaction state?
- Are there any circumstances in which non recoverable schedules are desirable explain?
- Are there any circumstances under which it would be desirable to allow non Cascadeless schedule explain your answer?
- What is recovery and atomicity in DBMS?
- How many non serial schedules are serializable?
- What is serializable schedule in DBMS?
What is non-serial schedule in DBMS?
This is a type of Scheduling where the operations of multiple transactions are interleaved. ... Unlike the serial schedule where one transaction must wait for another to complete all its operation, in the non-serial schedule, the other transaction proceeds without waiting for the previous transaction to complete.
Which are recoverable and Cascadeless schedules?
Note that Cascadeless schedule allows only committed read operations. However, it allows uncommitted write operations. Also note that Cascadeless Schedules are always recoverable, but all recoverable transactions may not be Cascadeless Schedule.
What is a recoverable schedule is one where?
Recoverable Schedules:
Schedules in which transactions commit only after all transactions whose changes they read commit are called recoverable schedules. In other words, if some transaction Tj is reading value updated or written by some other transaction Ti, then the commit of Tj must occur after the commit of Ti.
What is serializable & non serializable schedule?
Serializable schedule
It identifies which schedules are correct when executions of the transaction have interleaving of their operations. A non-serial schedule will be serializable if its result is equal to the result of its transactions executed serially.
What is non recoverable schedule?
A non recoverable schedule means: When there is a system failures, we may not be able to recover to a consistent database state.
What is the mean of recoverable schedule?
If the commit operation of the transaction performing the dirty read is delayed till the commit or abort operation of the transaction which updated the value, then the schedule is recoverable.
What do you mean by Cascadeless schedules?
If in a schedule, a transaction is not allowed to read a data item until the last transaction that has written it is committed or aborted, then such a schedule is called as a Cascadeless Schedule. In other words, Cascadeless schedule allows only committed read operations.
Which of the following is not a transaction state?
Which of the following is not a transaction state? Explanation: Compensated is not a transaction state. But active, partially committed and failed are different states of a transaction. Explanation: The execution sequences in concurrency control are known as schedules.
Are there any circumstances in which non recoverable schedules are desirable explain?
Non recoverable schedules may sometimes be needed when updates must be made visible early due to time constraints, even if they have not yet been committed, which may be required for every long duration transactions.
Are there any circumstances under which it would be desirable to allow non Cascadeless schedule explain your answer?
Are there any circumstances under which it would be desirable to allow non- cascadeless schedules? Explain your answer. ... Cascadeless schedules are desirable because the failure of a transaction does not lead to the aborting of any other transaction. Of course this comes at the cost of less concurrency.
What is recovery and atomicity in DBMS?
Recovery and Atomicity
Transactions are made of various operations, which are atomic in nature. ... A transaction may be in the middle of some operation; the DBMS must ensure the atomicity of the transaction in this case. It should check whether the transaction can be completed now or it needs to be rolled back.
How many non serial schedules are serializable?
Two schedules (one being serial schedule and another being non-serial) are said to be conflict serializable if the conflict operations in both the schedules are executed in the same order.
What is serializable schedule in DBMS?
A serializable schedule is a schedule whose effect on any consistent database instance is guaranteed to be identical to that of some complete serial schedule over S. Example 2. T1.
