Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-5
CRE
with the address at which the backup must start processing if the primary stops. See
also data-state information and process pair.
CRE. See Common Run-Time Environment (CRE).
critical event. A Distributed Systems Management (DSM) event that is considered to be
crucial to the operation of the system or network or that could have potentially serious
consequences, such as the loss of a device. Each subsystem determines which of its
events are critical by including a unique EMS token in the event message. See also
action event, Event Management Service (EMS), and information event.
DAL server. See Data Access Language (DAL) server.
Data Access Language (DAL) server. A nonprivileged, single-threaded, host-based data
server process running on an HP system that uses both SQL and DAL features. It
provides Macintosh users on attached LANs with reliable, transparent, fault-tolerant,
distributed access to data residing in HP NonStop SQL/MP databases.
database. A collection of tables containing data, all objects that depend on the tables, and
all catalogs in which the tables and objects are registered.
database consistency. The state of a database in which items satisfy established criteria.
For example, an account balance must equal credits to the balance minus debits to the
balance. When the database satisfies these criteria, the database is considered to be
consistent. In general, a database is consistent when it is accurate and all changes
generated by transactions are complete. Database consistency is defined by the
application, which establishes the values and relationships of database fields and
records.
database snapshot. A copy of a database frozen on disk to allow record taking and other
read-only activities to be done against a consistent copy of the database while
transaction processing continues against the original database.
data definition language (DDL). The set of definition statements within the SQL language.
Data definition statements are used to define, delete, or modify the catalog definition of
a table, column, index, view, constraint, or partition or to change the authorization.
data integrity. The condition of a database when its data values are accurate, valid, and
consistent, according to rules established for changing the database. See also
database consistency.
data-state information. Information provided by a primary process to a backup process
that operates as the other half of a process pair. This information provides the backup
with enough of the primary’s data to be able to transparently take over processing
without losing or corrupting data values. See also control-state information and process
pair.
DBBL. See distinguished bulletin board liaison (DBBL).