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Online transaction processing _OLTP_

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					Online transaction processing (OLTP)
 ?Online transaction processing (OLTP) is that use of computer networks, will be
distributed in different geographical business address and business computer
equipment or network management Zhongxin network connection, so that any one
network node in Zai on both Jinxingtongyi, Shi Shi's business address
Huodong or services.
   ?Usually in the database system, the transaction is a discrete unit of work. For
example, a database transaction can modify a user's account balance or
stock item write. Online transaction processing systems (OLTP) collecting and
processing real-time data services connected and sharing the database and change the
status of other documents. In online transaction processing, transactions are executed
immediately, which batch the contrary, a number of matters to be stored for some time,
and then be executed. Most of the batch (for example, the exchange account) is
carried out at night. OLTP results can be obtained immediately in the database,
assuming the transaction can be completed. Online transaction processing occurs in
real-time way. Sector enterprises account will be zero storage characteristics and the
related collection and management departments on-line transaction processing
systems example.
    In a single user, single database environment, the implementation of affairs is
simple, it is because there is no conflict between the database synchronization
problems or needs. In a distributed environment, maintaining the integrity of multiple
databases is another problem. Traditionally, most of the online transaction processing
system implemented on a large computer system, which is the operation because of its
complexity, and the need for fast input / output, the reasons for the prohibition and
management. If a transaction must be modified in a number of venues, it will need to
rewrite the data management system to prevent and provide synchronization. Other
requirements include a paper's capacity to return to failure to provide
security features, and, if necessary, to provide data recovery capabilities. This is done
by a transaction supervisor to deal with. The supervisor to ensure the transaction is
fully completed, or to rollback, and therefore can guarantee the correctness of the
database state.
    In a distributed environment, often in parallel write operations on the database
server in place several. This requires a complicated transaction
"rollback" mechanism to ensure that a write operation in case of
system failure, is still to ensure the integrity of the database. Services or with the
confirmation, or give up. If one or more and affairs of the system response is
inconsistent, which means that there may be a system or communication failure,
which would abandon a transaction.
    Can be seen, when multiple users try to change the same piece of data when a
conflict arises. In addition, multiple databases must be synchronized write operations,
and must ensure that the write has actually been disposed of all of the database, and
need a monitoring program to ensure data integrity. In the distributed transaction
processing environment there are four requirements, together known as the
"ACID".
     Atomic (Atomicity): definition of an independent unit of work. If a transaction is
distributed, all affect the separation of the sub-location data services must be like to
be together as a transaction execution. In order to maintain consistency of data in
multiple locations, will need to use the following description of the two-stage
approval process.
     Consistency (Consistency): Consistency is basically a database change from one
state to another state the same requirements. Services supervisor must verify all the
affected data are consistent.
     Isolation (Isolation): Services must be implemented in isolation until the
completion of the implementation period is not affected by other matters.
     Sustainability (Durability): The nature of the transaction is carried out with the
final confirmation. Once a transaction has been tested to all the affected systems are
correct, it is recognized and no longer need to rollback.
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