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What is control techniques?
several problems can occur when concurrent transaction execute in an uncontrolled manner.
What are the three most common concurrent transaction execution problems?
The three most common concurrent transaction executive problems are uncommitted data, lost updates, and inconsistent retrievals. It is believed that concurrency control can help these problems.
What is concurrency control techniques?
several problems can occur when concurrent transaction execute in an uncontrolled manner.
What is concurrent execution of transaction in dbms?
Concurrent Execution in DBMSDatabase Management systems usually allow multiple transaction to run concurrently even though it causes a lot of complications with consistency of data. Ensuring consistency when multiple transactions execute concurrently, requires extra effort. It is much simpler to allow only one transaction to run at a time but concurrent execution of transactions has its own advantages: Improved throughput and resource utilization :Concurrent execution means that CPU doesn't have to be idle while it is waiting for I/O activity to complete. This is because transactions can run in parallel on CPU along with I/O activities. This means that resources can be utilized effectively by having multiple transaction run concurrently.Less waiting time : Without concurrency, a short transaction might need to wait for a long transaction to finish causing delay in its execution. With multiple transactions running on the system, new transactions have to wait for less time before getting executed.
What is the different between concurrent and non concurret force?
Concurrent forces have a common point of intersection while non concurrent forces do not have a common point of intersection. Moreover concurrent forces act along the same line while non concurrent forces do not.
What is a concurrent session?
Concurrent session (or sentence) means 2 different sessions (or sentences) that will run at the exact same time.
What type of powers deal with many different areas of state authority?
its either concurrent, inherent, implied, or reserved
What is a concurrent forces?
Non concurrent forces are those forces that do not have a common point of intersection and act along different lines of action.
What are the key characteristics of transaction cost economies?
Atomicity. A transaction must be an atomic unit of work (either all of its data modifications are performed, or none of them is performed).Consistency. When completed, a transaction must leave all data in a consistent state. In a relational database, all rules must be applied to the transaction's modifications in order to maintain all data integrity. All internal data structures, such as B-tree indexes or doubly linked lists, must be correct at the end of the transaction.Isolation. Modifications made by concurrent transactions must be isolated from the modifications made by any other concurrent transactions. A transaction either sees data in the state it was in before another concurrent transaction modified it or it sees the data after the second transaction has completed, but it does not see an intermediate state. This situation is referred to as serializability, because it results in the capability to reload the starting data and replay a series of transactions in order to end up with the data in the same state it was in after the original transactions were performed.Durability. After a transaction has completed, its effects are permanently in place in the system. The modifications persist even in the event of a system failure.
What is a non concurrent force?
Non concurrent forces are those forces that do not have a common point of intersection and act along different lines of action.
Difference between serial and non-serial schedule?
Serial ScheduleNon-Serial ScheduleA serial schedule is a sequence of operation by a set of concurrent transaction that preserves the order of operations in each of the individual transactions.A non-serial schedule is a schedule where the operations of a group of concurrent transactions are interleaved.Transactions are performed in serial order.Transactions are performed in non-serial order, but result should be same as serial.No interference between transactionsConcurrency problem can arise here.It does not matter which transaction is executed first, as long as every transaction is executed in its entirely from the beginning to end.The problem we have seen earlier lost update, uncommitted data, inconsistent analysis is arise if scheduling is not proper.A serial schedule gives the benefits of concurrent execution without any problemIn this schedule there is no any benefit of concurrent execution.Serial schedule that does interleaved the actions of different transactions.Where non-serial schedule has no only fix actions of any transaction.EXAMPLE:If some transaction T is long, the other transaction must wait for T to complete all its operations.EXAMPLE:In this schedule the execution of other transaction goes on without waiting the completion of T.If we consider transaction to be independent serial schedule is correct based on (property ACID) above assumption is valid.The objective behind serializability is to find the non-serial schedule that allows transactions to execute concurrently without interfering one another.
What types of anomalies are found in relational database?
There are 3types 1) Update Anomalies 2) Insertion Anomalies 3) Deletion Anomalies
