Databases, Chapter 12

In a DDBMS, the software component on each computer that requests data. The TP is responsible for the execution and coordination of all database requests issued by a local application that accesses data on any DP.

A data consistency model in which data changes are not immediate but propagate slowly through the system until all replicas are eventually consistent.

A data allocation strategy in which the entire database is stored at one site.

A hardware and software system composed of clients, servers, and middleware. Features a user of resources (client) and a provider of resources (server).

The transaction processor (TP) node that coordinates the execution of a two-phase COMMIT in a DDBMS.

In a distributed DBMS, the process of deciding where to locate data fragments.

A characteristic of a DDBMS that allows a single object to be broken into two or more segments or fragments. The object might be a user’s database, a system database, or a table. Each fragment can be stored at any site on a computer network.

The resident software component that stores and retrieves data through a DDBMS. The DP is responsible for managing the local data in the computer and coordinating access to that data.

The storage of duplicated database fragments at multiple sites on a DDBMS. Duplication of the fragments is transparent to the end user. Data replication provides fault tolerance and performance enhancements.

A subset of a distributed database. Although the fragments may be stored at different sites within a computer network, the set of all fragments is treated as a single database.

A logically related database that is stored in two or more physically independent sites.

A data dictionary that contains the description (fragment names and locations) of a distributed database.

A data dictionary that contains the description (fragment names and locations) of a distributed database.

A DBMS that supports a database distributed across several different sites; a DDBMS governs the storage and processing of logically related data over interconnected computer systems in which both data and processing functions are distributed among several sites.

The database schema description of a distributed database as seen by the database administrator.

Sharing the logical processing of a database over two or more sites connected by a network.

A database request that allows a single SQL statement to access data in several remote data processors (DPs) in a distributed database.

A database transaction that accesses data in several remote data processors (DPs) in a distributed database.

A DDBMS feature that allows a distributed database to look like a single logical database to an end user.

A protocol used by a data processor (DP) to roll back or roll forward transactions with the help of a system’s transaction log entries.

A feature that allows continuous operation of a DDBMS, even if a network node fails.

A DDBMS feature that allows a system to treat a distributed database as a single database even though it is divided into two or more fragments.

A system that integrates different types of database management systems (hierarchical, network, and relational) over a network. It supports different database management systems that may even support different data models running under different computer systems.

In a DDBMS, the distributed database that stores multiple copies of each database fragment at multiple sites.

A feature that allows a system to integrate several centralized DBMSs into one logical DDBMS.

A system that integrates different types of centralized database management systems over a network.

A system that integrates only one type of centralized database management system over a network.

The distributed database design process that breaks a table into subsets of unique rows.

A property of a DDBMS in which database access requires the user to know both the name and location of the fragments.

A property of a DDBMS in which database access requires the user to know only the name of the database fragments. (Fragment locations need not be known.)

A combination of horizontal and vertical strategies for data fragmentation, in which a table may be divided into several rows and each row has a subset of the attributes (columns).

A scenario describing a fully distributed database management system with support for multiple data processors and transaction processors at multiple sites.

A scenario in which multiple processes run on different computers sharing a single data repository.

A data replication rule that requires all copies of data fragments to be identical.

The delay imposed by the amount of time required for a data packet to make a round trip from point A to point B.

The delay that occurs when nodes become suddenly unavailable due to a network failure. In distributed databases, the system must account for the possibility of this condition.

A database model that attempts to provide ACID-compliant transactions across a highly distributed infrastructure.

A distributed database in which copies of only some database fragments are stored at multiple sites.

In partitioned databases, one or more attributes in a table that determine the fragment in which a row will be stored.

A data allocation strategy of dividing a database into two or more fragments that are stored at two or more sites.

A DDBMS feature that allows a system to perform as though it were a centralized DBMS.

A DDBMS feature that allows a single SQL statement to access data in a single remote DP.

A DDBMS feature that allows a transaction (formed by several requests) to access data in a single remote DP.

The DDBMS’s ability to hide the existence of multiple copies of data from the user.

A data allocation strategy in which copies of one or more database fragments are stored at several sites.

A scenario in which all processing is done on a single host computer and all data is stored on the host computer’s local disk.

In a DDBMS, a data processor (DP) node that participates in a distributed transaction using the two-phase COMMIT protocol.

A DDBMS property that ensures database transactions will maintain the distributed database’s integrity and consistency, and that a transaction will be completed only when all database sites involved complete their part of the transaction.

In a DDBMS, an algorithm used to ensure atomicity of transactions and database consistency as well as integrity in distributed transactions.

In a DDBMS, a condition in which each row is unique, regardless of which fragment it is located in.

A distributed database in which each database fragment is stored at a single site.

In distributed database design, the process that breaks a table into a subset of columns from the original table. Fragments must share a common primary key.

A protocol that ensures transaction logs are written to permanent storage before any database data is actually updated.