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Glossary

D

DARI
Database Application Remote Interface. Former term for stored procedure.

data area
A memory area used by a program to hold information.

database administrator (DBA)
An individual responsible for the design, development, operation, safeguarding, maintenance, and use of a database. (T)

Database Application Remote Interface (DARI)
Former term for stored procedure.

database client
A workstation used to access a database residing on a database server.

database connection services (DCS) directory
A directory that contains entries for remote databases and the corresponding application requester used to access them.

database directory
A directory that contains database access information for all databases to which a client can connect.

database engine
The part of the database manager providing the base functions and configuration files needed to use the database.

database log
A set of primary and secondary log files consisting of log records that record all changes to a database. The database log is used to roll back changes for units of work that are not committed and to recover a database to a consistent state. See also primary log, secondary log.

database managed space (DMS) table space
A table space whose space is managed by the database. Contrast with system managed space (SMS) table space.

database management system (DBMS)
Synonym for database manager.

database manager
A computer program that manages data by providing the services of centralized control, data independence, and complex physical structures for efficient access, integrity, recovery, concurrency control, privacy, and security.

database manager instance
A logical database manager environment similar to an image of the actual database manager environment. You can have several instances of the database manager product on the same workstation. You can use these instances to separate the development environment from the production environment, tune the database manager to a particular environment, and protect sensitive information from a particular group of people.

database object
Anything that can be created or manipulated with SQL--for example, tables, views, indexes, packages, triggers, or table spaces.

database partition
A part of the database that consists of its own user data, indexes, configuration files, and transaction logs. Sometimes called a node or database node.

database server
A functional unit that provides database services for databases.

database system monitor
A collection of programming APIs that monitor performance and status information about the database manager, databases, and applications using the database manager and DB2 Connect.

data definition language (DDL)
A language for describing data and its relationships in a database. Synonymous with data description language. (T)

data description language
Synonym for data definition language. (T)

data enhancement
The modification of data as it is copied between the base table and the target table, including:

DataJoiner
A separately available product that provides client applications integrated access to distributed data and provides a single database image of a heterogeneous environment. With DataJoiner, a client application can join data that is distributed across multiple database management systems (using a single SQL statement) or update a single remote data source, as if the data were local.

data link control (DLC)
In SNA, the protocol layer that consists of the link stations that schedule data transfer over a link between two nodes and perform error control for the link.

data manipulation language (DML)
A subset of SQL statements used to manipulate data.

date
A three-part value that designates a day, month, and year.

date duration
A DECIMAL(8,0) value that represents a number of years, months, and days.

datetime value
A value of the data type DATE, TIME, or TIMESTAMP.

DB2 CLI
DB2 Call Level Interface. An alternative SQL interface for the DB2 family of products that takes full advantage of DB2 capability.

DB2 Connect
A product that provides the function necessary (DRDA application requester support) for client applications to read and update data stored in DRDA application servers, such as other members of the DB2 family.

DB2 SDK
DB2 Software Developer's Kit.

DB2 Software Developer's Kit (DB2 SDK)
A collection of tools that help developers create database applications.

DB2UEXIT
An optional, user-written executable program that the database manager invokes to move or retrieve archive log files.

DBA
Database administrator.

DBA Utility
A tool that lets DB2 users configure databases and database manager instances, manage the directories necessary for accessing local and remote databases, back up and recover databases or table spaces, and manage media on a system using a graphical interface. The tasks provided by this tool can be accessed from the Control Center.

DBCLOB
Double-byte character large object.

DBCS
Double-byte character set.

DBMS
Database management system.

DBMS instance connection
A logical connection between an application and an agent process or thread owned by a DB2 instance.

DCE**
Distributed Computing Environment.

DDL
Data definition language.

deadlock
A condition under which a transaction cannot proceed because it is dependent on exclusive resources that are locked by some other transaction, which in turn is dependent on exclusive resources in use by the original transaction.

deadlock detector
A process within the database manager that monitors the states of the locks to determine if a deadlock condition has occurred. When a deadlock condition is detected, the detector stops one of the transactions involved in the deadlock. This transaction is rolled back and the other transactions proceed.

delete rule
A rule associated with a referential constraint that either restricts the deletion of a parent row or specifies the effect of such a deletion on the dependent rows.

delimited identifier
A sequence of characters enclosed within quotation marks ("). The sequence must consist of a letter followed by zero or more characters, each of which is a letter, digit, or the underscore character.

delimiter
A character or flag that groups or separates items of data.

delimiter token
A string constant, a delimited identifier, an operator symbol, or any of the special characters shown in syntax diagrams.

dependent logical unit (DLU)
An LU that requires assistance from a system services control point (SSCP) to instantiate an LU-LU session.

dependent row
A row containing a foreign key that matches the value of a parent key in the parent row. The foreign key value thus represents a reference from the dependent row to the parent row.

dependent table
A table that is a dependent in at least one referential constraint.

descendent row
A row that is dependent on another row or a row that is a descendent of a dependent row.

descendent table
A table that is a dependent of another table or a descendent of a dependent table.

deterministic function
See not-variant function.

device name
A name reserved by the system, or a device driver that refers to a specific device.

directed join
A relational operation in which all of the rows in one or both of the joined tables are rehashed and directed to new database partitions based on the join predicate. If all of the partitioning key columns in a table participate in the equijoin predicates, the other table is rehashed; otherwise (if there is at least one equijoin predicate), both tables are rehashed.

directory services
A portion of the APPN protocols that maintains information about the location of resources in an APPN network.

distinct type
A user-defined data type that is internally represented as an existing type (its source type), but is considered to be a separate and incompatible type for semantic purposes.

Distributed Computing Environment (DCE**)
A set of services and tools that support the creation, use, and maintenance of distributed applications in a heterogeneous computing environment. DCE is independent of the operating system and network; it provides interoperability and portability across heterogeneous platforms.

distributed directory database
The complete listing of all the resources in the network as maintained in the individual directories scattered throughout an APPN network. Each node has a piece of the complete directory, but it is not necessary for any one node to have the entire list. Entries are created, modified, and deleted through system definition, operator action, automatic registration, and ongoing network search procedures. Synonymous with distributed network directory.

distributed network directory
Synonym for distributed directory database.

distributed relational database
A database whose tables are stored on different but interconnected computing systems.

Distributed Relational Database Architecture (DRDA)
Architecture that defines formats and protocols for providing transparent access to remote data. DRDA defines two types of functions, the application requester function and the application server function.

distributed unit of work (DUOW)
A unit of work that allows SQL statements to be submitted to multiple relational database management systems, but no more than one system per SQL statement.

DLC
Data link control.

DLU
Dependent logical unit.

DML
Data manipulation language.

DMS table space
Database managed space table space.

DNS
Domain name system.

Domain Name
A mechanism, in TCP/IP, that tracks the host names in a network. A domain name consists of a sequence of names separated by dots.

Domain Name System
The distributed database system used by TCP/IP to map human-readable machine names into IP addresses.

double-byte character large object (DBCLOB)
A sequence of double-byte characters, where the size can be up to 2 gigabytes. A data type that can be used to store large double-byte text objects. Also called double-byte character large object string. Such a string always has an associated code page.

double-byte character set (DBCS)
A set of characters in which each character is represented by two bytes.

DRDA
Distributed Relational Database Architecture.

DUOW
Distributed unit of work.

dynamic SQL
SQL statements that are prepared and run within a running program. In dynamic SQL, the SQL source is contained in host language variables rather than being coded into the program. The SQL statement might change several times while the program is running.

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