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Multiversion Concurrency Control
Multiversion concurrency control (MCC or MVCC), is a concurrency control method commonly used by database management systems to provide concurrent access to the database and in programming languages to implement transactional memory. Description Without concurrency control, if someone is reading from a database at the same time as someone else is writing to it, it is possible that the reader will see a half-written or inconsistent piece of data. For instance, when making a wire transfer between two bank accounts if a reader reads the balance at the bank when the money has been withdrawn from the original account and before it was deposited in the destination account, it would seem that money has disappeared from the bank. Isolation is the property that provides guarantees in the concurrent accesses to data. Isolation is implemented by means of a concurrency control protocol. The simplest way is to make all readers wait until the writer is done, which is known as a read-write lock. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 computing, concurrent operations are generated, while getting those results as quickly as possible. Computer systems, both software and computer hardware, hardware, consist of modules, or components. Each component is designed to operate correctly, i.e., to obey or to meet certain consistency rules. When components that operate concurrently interact by messaging or by sharing accessed data (in Computer memory, memory or Computer data storage, storage), a certain component's consistency may be violated by another component. The general area of concurrency control provides rules, methods, design methodologies, and Scientific theory, theories to maintain the consistency of components operating concurrently while interacting, and thus the consistency and correctness of the who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Corporation Of America
Computer Corporation of America (CCA) was a computer software and database systems company founded in 1965. It was best known for its Model 204 (M204) database system for IBM and compatible mainframes. It was acquired by Rocket Software in 2010.http://www.ebizq.net/news/12526.html; acquired June 13, 2010 Corporate history Founded in 1965, Computer Corporation of America (CCA) was a computer software and database systems. with offices in Technology Square, Kendall Square, Cambridge, Massachusetts. Their primary database product, first deployed in 1972, was Model 204 (M204), which ran on IBM mainframes. It incorporates a programming language and an environment for application development. CCA operated the ARPANET Datacomputer. In 1992, CCA purchased the System 1022 and System 1032 assets of Software House; these database systems were designed for Digital Equipment Corporation's PDP-10 and VAX systems, respectively. In 1984, CCA was purchased by Crowntek, a Toronto-based comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 computing, concurrent operations are generated, while getting those results as quickly as possible. Computer systems, both software and computer hardware, hardware, consist of modules, or components. Each component is designed to operate correctly, i.e., to obey or to meet certain consistency rules. When components that operate concurrently interact by messaging or by sharing accessed data (in Computer memory, memory or Computer data storage, storage), a certain component's consistency may be violated by another component. The general area of concurrency control provides rules, methods, design methodologies, and Scientific theory, theories to maintain the consistency of components operating concurrently while interacting, and thus the consistency and correctness of the who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Version Control
In software engineering, version control (also known as revision control, source control, or source code management) is a class of systems responsible for managing changes to computer programs, documents, large web sites, or other collections of information. Version control is a component of software configuration management. Changes are usually identified by a number or letter code, termed the "revision number", "revision level", or simply "revision". For example, an initial set of files is "revision 1". When the first change is made, the resulting set is "revision 2", and so on. Each revision is associated with a timestamp and the person making the change. Revisions can be compared, restored, and, with some types of files, merged. The need for a logical way to organize and control revisions has existed for almost as long as writing has existed, but revision control became much more important, and complicated, when the era of computing began. The numbering of book editions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector Clock
A vector clock is a data structure used for determining the partial ordering of events in a distributed system and detecting causality violations. Just as in Lamport timestamps, inter-process messages contain the state of the sending process's logical clock. A vector clock of a system of ''N'' processes is an array/vector of ''N'' logical clocks, one clock per process; a local "largest possible values" copy of the global clock-array is kept in each process. Denote VC_i as the vector clock maintained by process i, the clock updates proceed as follows: * Initially all clocks are zero. * Each time a process experiences an internal event, it increments its own logical clock in the vector by one. For instance, upon an event at process i, it updates VC_ \leftarrow VC_ + 1. * Each time a process sends a message, it increments its own logical clock in the vector by one (as in the bullet above, but not twice for the same event) and then the message piggybacks a copy of its own vector. * E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamp-based Concurrency Control
In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some databases to safely handle transactions, using timestamps. Operation Assumptions * Every timestamp value is unique and accurately represents an instant in time. * A higher-valued timestamp occurs later in time than a lower-valued timestamp. Generating a timestamp A number of different ways have been used to generate timestamp * Use the value of the system's clock at the start of a transaction as the timestamp. * Use a thread-safe shared counter that is incremented at the start of a transaction as the timestamp. * A combination of the above two methods. Formal Each transaction (T_i) is an ordered list of actions (A_). Before the transaction performs its first action (A_), it is marked with the current timestamp, or any other strictly totally ordered sequence: TS(T_i) = NOW(). Every transaction is also given an initially empty set of transactions upon wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Read-copy-update
In computer science, read-copy-update (RCU) is a synchronization mechanism that avoids the use of lock primitives while multiple threads concurrently read and update elements that are linked through pointers and that belong to shared data structures (e.g., linked lists, trees, hash tables). Whenever a thread is inserting or deleting elements of data structures in shared memory, all readers are guaranteed to see and traverse either the older or the new structure, therefore avoiding inconsistencies (e.g., dereferencing null pointers). It is used when performance of reads is crucial and is an example of space–time tradeoff, enabling fast operations at the cost of more space. This makes all readers proceed as if there were no synchronization involved, hence they will be fast, but also making updates more difficult. Name and overview The name comes from the way that RCU is used to update a linked structure in place. A thread wishing to do this uses the following steps: * create a new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Databases Using MVCC
The following database management systems and other software use multiversion concurrency control. Databases * Altibase * Berkeley DB * Cloudant * Cloud Spanner * Clustrix * CockroachDB * Couchbase * CouchDB * CUBRID * IBM Db2 – since IBM DB2 9.7 LUW ("Cobra") under CS isolation level – in ''currently committed'' modeDB2 Version 9.7 LUW Information CenterCurrently committed semantics improve concurrency/ref> * Drizzle * Druid * etcd * EXASOL * eXtremeDB * Firebird * FLAIM * FoundationDB * GE Smallworld Version Managed Data Store * H2 Database Engine – experimental since version 1.0.57 (2007-08-25) * HBase * HSQLDB – starting with version 2.0 * IBM Netezza * Ingres * InterBase – all versions * LMDB and MDBX * MariaDB (MySQL fork) – when used with XtraDB, an InnoDB fork and that is included in MariaDB sources and binaries oPBXT* MarkLogic Server – a bit of this is described in * MemSQL * Microsoft SQL Server – when using READ_COMMITTED_SNAPSHOT, startin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
InterBase
InterBase is a relational database management system (RDBMS) currently developed and marketed by Embarcadero Technologies. InterBase is distinguished from other RDBMSs by its small footprint, close to zero administration requirements, and multi-generational architecture. InterBase runs on the Microsoft Windows, macOS, Linux, Solaris operating systems as well as iOS and Android. Technology InterBase is a SQL-92-compliant relational database and supports standard interfaces such as JDBC, ODBC, and ADO.NET. Small footprint A full InterBase server installation requires around 40 MB on disk. A minimum InterBase client install requires about 400 KB of disk space. Embedded or server InterBase can be run as an embedded database or regular server. Data controller friendly inbuilt encryption Since InterBase XE, InterBase includes 256bit AES strength encryption that offers full database, table or column data encryption. This assists data controllers conform with data protection law ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jim Starkey
Jim Starkey (born January 6, 1949 in Illinois) is a database architect responsible for developing InterBase, the first relational database to support multi-versioning,Babcock, Charles"MySQL Database to Get Replication Monitoring, Multiversioning Concurrency Features."InformationWeek. Sept. 14, 2007. Accessed Dec. 7, 2012 the blob column type, type event alerts, arrays and triggers.Niccolai, James"Update: MySQL buys company, hires noted architect."Computer World. Feb. 27, 2006. Accessed Dec. 7, 2012 Starkey is the founder of several companies, including the web application development and database tool company Netfrastructure and NuoDB. Education and career Jim Starkey graduated from University of Wisconsin at Madison, Wisconsin, with a Bachelor of Arts in Mathematics. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the mid-1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in the late 1980s, especially wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oracle Rdb
Oracle Rdb is a relational database management system for the OpenVMS operating system. It was originally released by Digital Equipment Corporation (DEC) in 1984 as VAX Rdb/VMS. Product history Rdb was a component of the ''VAX Information Architecture'', and was designed to interoperate with other Digital database tools and application frameworks such as the Application Control Management System, Datatrieve and the Common Data Dictionary. It originally provided a proprietary query interface known as the Relational Data Operator (RDO), but later gained support for ANSI SQL. In 1994 DEC sold the Rdb division to Oracle Corporation where it was rebranded Oracle Rdb. As of 2020, Oracle is still actively developing Rdb, with over half of the codebase developed under Oracle's ownership. Version 7.0 ran on OpenVMS for VAX and Alpha, version 7.1 on Alpha only, and versions 7.2 to 7.4 on Alpha and IA-64 (Itanium). Rdb featured one of the first cost-based optimizers, and after acqui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
