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Apache HBase Internals: Locking and Multiversion Concurrency Control - Cloudera Engineering Blog

PostgreSQL's Multi-Version Concurrency Control

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http://qatestlab.com/ A software testing company distinguishes 3 patterns of handling software concurrency issues. They are: pessimistic pattern of concurrency control, optimistic pattern of concurrency control and pattern with no control of concurrency issues.

Contents: 1. Introduction to Database Management Systems 2. Database Design and Normalization 3. Relational Algebra & Relational Calculus 4. Query Languages-SQL 5. Internal Structure and Organization of Data 6. Transaction Processing 7. Concurrency Control and Recovery P. Paper

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Checkout a session: The next step is to checkout a session. Access control rules determine which users are allowed to checkout a session to which accounts on which systems. Alternately, a user can request one-time access. In either case, concurrency limits may be in place, for example to ensure that no more than two administrators work on the same system at the same time. See more at: http://hitachi-id.com/privileged-access-manager/overview/screen-shots.html

Checkout a session: (Click to enlarge) Checkout a session: The next step is to checkout a session. Access control rules determine which users are allowed to checkout a session to which accounts on which systems. Alternately, a user can request one-time access (authorized through a workflow process). In either case, concurrency limits may be in place, for example to ensure that no more than two administrators work on the same system at the same time.