Global concurrency control
Encyclopedia
Global concurrency control typically pertains to the concurrency control
of a system comprising several components, each with its own concurrency control. The overall concurrency control of the whole system, the Global concurrency control, is determined by the concurrency control of its components, module
s. In this case also the term Modular concurrency control is used.
In many cases a system may be distributed over a communication network. In this case we deal with distributed concurrency control
of the system, and the two terms sometimes overlap. However, distributed concurrency control typically relates to a case where the distributed system's components do not have each concurrency control of its own, but rather are involved with a concurrency control mechanism that spans several components in order to operate. For example, as typical in a distributed database.
In database systems and transaction processing
(transaction management) global concurrency control relates to the concurrency control of a multidatabase system (for example, a Federated database; other examples are Grid computing
and Cloud computing
environments). It deals with the properties of the global schedule
, which is the unified schedule of the multidatabase system, comprising all the individual schedules of the database system
s and possibly other transactional objects in the system. A major goal for global concurrency control is Global serializability
(or Modular serializability). The problem of achieving global serializability in a heterogeneous environment had been open
for many years, until an effective solution based on Commitment ordering
(CO) has been proposed (see Global serializability
). Global concurrency control deals also with relaxed forms of global serializability which compromise global serializability (and in many applications also correctness, and thus are avoided there). While local (to a database system) relaxed serializability methods compromise serializability for performance gain (utilized when the application allows), it is unclear that the various proposed relaxed global serializability methods provide any performance gain over CO, which guarantees global serializability.
Concurrency control
In information technology and computer science, especially in the fields of computer programming , operating systems , multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, while getting those results as quickly as possible.Computer...
of a system comprising several components, each with its own concurrency control. The overall concurrency control of the whole system, the Global concurrency control, is determined by the concurrency control of its components, module
Modular programming
Modular programming is a software design technique that increases the extent to which software is composed of separate, interchangeable components called modules by breaking down program functions into modules, each of which accomplishes one function and contains everything necessary to accomplish...
s. In this case also the term Modular concurrency control is used.
In many cases a system may be distributed over a communication network. In this case we deal with distributed concurrency control
Distributed concurrency control
Distributed concurrency control is the concurrency control of a system distributed over a computer network ....
of the system, and the two terms sometimes overlap. However, distributed concurrency control typically relates to a case where the distributed system's components do not have each concurrency control of its own, but rather are involved with a concurrency control mechanism that spans several components in order to operate. For example, as typical in a distributed database.
In database systems and transaction processing
Transaction processing
In computer science, transaction processing is information processing that is divided into individual, indivisible operations, called transactions. Each transaction must succeed or fail as a complete unit; it cannot remain in an intermediate state...
(transaction management) global concurrency control relates to the concurrency control of a multidatabase system (for example, a Federated database; other examples are Grid computing
Grid computing
Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...
and Cloud computing
Cloud computing
Cloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network ....
environments). It deals with the properties of the global schedule
Schedule (computer science)
In the fields of databases and transaction processing , a schedule of a system is an abstract model to describe execution of transactions running in the system. Often it is a list of operations ordered by time, performed by a set of transactions that are executed together in the system...
, which is the unified schedule of the multidatabase system, comprising all the individual schedules of the database system
Database system
A database system is a term that is typically used to encapsulate the constructs of a data model, database Management system and database....
s and possibly other transactional objects in the system. A major goal for global concurrency control is Global serializability
Global serializability
In concurrency control of databases, transaction processing , and other transactional distributed applications, Global serializability is a property of a global schedule of transactions...
(or Modular serializability). The problem of achieving global serializability in a heterogeneous environment had been open
Open problem
In science and mathematics, an open problem or an open question is a known problem that can be accurately stated, and has not yet been solved . Some questions remain unanswered for centuries before solutions are found...
for many years, until an effective solution based on Commitment ordering
Commitment ordering
In concurrency control of databases, transaction processing , and related applications, Commitment ordering is a class of interoperable Serializability techniques, both centralized and distributed. It allows optimistic implementations...
(CO) has been proposed (see Global serializability
Global serializability
In concurrency control of databases, transaction processing , and other transactional distributed applications, Global serializability is a property of a global schedule of transactions...
). Global concurrency control deals also with relaxed forms of global serializability which compromise global serializability (and in many applications also correctness, and thus are avoided there). While local (to a database system) relaxed serializability methods compromise serializability for performance gain (utilized when the application allows), it is unclear that the various proposed relaxed global serializability methods provide any performance gain over CO, which guarantees global serializability.
See also
- Concurrency controlConcurrency controlIn information technology and computer science, especially in the fields of computer programming , operating systems , multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, while getting those results as quickly as possible.Computer...
- Global serializabilityGlobal serializabilityIn concurrency control of databases, transaction processing , and other transactional distributed applications, Global serializability is a property of a global schedule of transactions...
- Commitment orderingCommitment orderingIn concurrency control of databases, transaction processing , and related applications, Commitment ordering is a class of interoperable Serializability techniques, both centralized and distributed. It allows optimistic implementations...
- Distributed concurrency controlDistributed concurrency controlDistributed concurrency control is the concurrency control of a system distributed over a computer network ....