D

database

A collection of control files, datafiles, and redo logs.

database buffer cache

The portion of the SGA (System Global Area) where copies of the data blocks are cached in memory. See also System Global Area (SGA).

Database Configuration Assistant (DBCA)

A Java-based tool you can use to create Oracle databases. The DBCA can store and manage definitions of your databases in the form of templates that can be used to make copies of a database.

Database Control

A web-based component of the Enterprise Management Framework for managing Oracle Database 10g. The Database Control allows you to monitor and administer a single Oracle database instance or a single Real Application Cluster (RAC) environment.

database templates

XML-based documents that the DBCA creates to store information about database definitions. The documents contain everything the DBCA needs to create a database. See also Database Configuration Agent (DBCA).

Database Writer (DBWn)

The Oracle background process that is responsible for writing changed data block buffers from the database buffer cache back to the datafiles on disk.

data block

The smallest unit of disk allocation in data or temp files, composed of one or more file system blocks.

Data Control Language (DCL)

The category of SQL commands that control access to database objects, including the GRANT and REVOKE commands.

Data Definition Language (DDL)

The category of SQL commands used to create objects in the database, including CREATE, ALTER, and DROP.

datafiles

The physical database files that store the database's segments, such as tables, indexes, rollback, and partition.

Data Manipulation Language (DML)

The category of SQL commands used to create, modify, or remove data from a table, including INSERT, UPDATE, and DELETE.

DBCA

See Database Configuration Assistant (DBCA).

DBMS_DATAPUMP

The PL/SQL (Procedural Language SQL) package that is an API to the Data Pump.

DB Time

A cumulative measure of time spent by the database responding to user requests, including wait times for access to resources such as memory, disk, and CPU for all nonidle user sessions.

DBWn

See Database Writer (DBW n).

DCL

See Data Control Language (DCL).

DDL

See Data Definition Language (DDL).

deadlock

A special kind of lock conflict that prevents two or more transactions from completing because each transaction has a lock on a resource needed by the other transaction.

dedicated server

A type of connection in which every client connection has an associated dedicated server process on the machine where the Oracle server exists. See also Shared Server.

default role

A role initially enabled for every user session.

default tablespace

The tablespace where a user's tables and indexes are stored if not declared explicitly.

directory object

A database object that identifies a file system location. Directory objects are used by data pump jobs.

dispatcher

A process in an Oracle Shared Server environment that manages requests from one or more client connections.

DML

See Data Manipulation Language (DML).

dynamic service registration

The ability of an Oracle instance to automatically register its existence with a listener.