HP OpenVMS Systems Documentation
DB-CURRENT-RECORD-NAME: A database special register
containing the name of the record type of the current record of the run
unit. It contains spaces if there is no current record of the run unit.
DBA: See database administrator.
DBCS: See Database Control System.
dbkey: See database key.
DB-KEY: A database special register that holds the
dbkey of the record accessed by the last FETCH, STORE, or FIND
statement. This special register can be used to fine tune storage
strategies in the database.
DBMS: See database management system.
DBQ: See Database Query Utility.
DB-UWA: A database special register which serves as
the record delivery area that the Database Control System (DBCS) uses
to make data items available to your program.
DDL: See data definition languages.
de-edit: The logical removal of all editing characters
from a numeric edited data item in order to determine that item's
unedited numeric value.
deadlock: A database processing situation in which two
or more run units are stopped by conflicting requests for locked
DML: See data manipulation language.
DMU: See Dictionary Management Utility.
empty set: A database set occurrence containing no
EXCLUSIVE usage mode: The state of a realm in which it
cannot be accessed by a concurrent run unit.
FIXED member: A record, upon becoming a member of a
set occurrence of a FIXED set type, that must remain a member of that
set until it is erased from the database. Fixed set membership is
declared in the schema DDL. Compare with MANDATORY member.
INSERTION class: An attribute of member records that
describes how and when members are added to database sets. See also
AUTOMATIC member and MANUAL member.
journal file: A database file that contains all
records modified by a run unit, usually chronologically ordered. A
journal file allows reconstruction of the data to prefailure conditions
in case of database contamination due to system or program failures.
journaling: The act of creating, writing, or both, to
a journal file.
junction record: A record inserted between two records
of the same type. You can use a junction record to simulate what would
otherwise be an illegal set relationship for Oracle CODASYL DBMS, that is, a
record type being a member of a set that it owns. Also, using a
junction record helps avoid data redundancy and inconsistency.
keeplist: A list of database keys used by a run unit
to lock records for later reference.
locking: HP COBOL has facilities that allow
concurrent use of a database or a sequential, relative, or indexed file
without corrupting their records. RMS on OpenVMS VAX maintains locks on
a file, whereas RMS on OpenVMS Alpha maintains locks on files and
records. In Oracle CODASYL DBMS, locks are maintained on individual records,
entire realms, or both.
MANDATORY member: A record, upon becoming a member of
a set occurrence of a set type, must remain a member of that or some
other set occurrence of that set type until it is erased from the
database. MANDATORY set membership is declared in the schema. Compare
with FIXED member.
MANUAL member: A database record that becomes a member
of a given set by explicit direction of the application program using
the CONNECT statement. MANUAL set membership is declared in the schema.
member condition: The condition, for which a truth
value can be determined, that a database record is a member of one or
member record: A database record, other than the owner
record, included in the set. There may be one or more member record
types in a set. There may be zero or more member records in a set.
nonsingular set: A database set not owned by the
SYSTEM. See also SYSTEM-owned set and owner record.
null: A data attribute associated with currency
indicators and database key values. This attribute is independent of
the value of the contents of data items.
OPTIONAL member: A database record that does not
necessarily remain a permanent member of a set. Its membership in a set
may be changed using the DISCONNECT statement without its being deleted
from the database. OPTIONAL set membership is declared in the schema.
Oracle CDD/Repository: The central repository of information
about data elements, data structures, and relationships between data
structures. Oracle CDD/Repository is used by Oracle CODASYL DBMS, Datatrieve, and
HP COBOL. It does not contain actual data files. Rather, it
contains definitions of schemas, storage schemas, and subschemas.
Oracle CDD/Repository is available under a separate license.
owner record: The head of a group of database records
that make up a set. There can be only one record type as the owner for
each set type and one owner record occurrence for each set occurrence.
PROTECTED usage mode: The state of a realm in which it
may be retrieved from but cannot be modified by concurrent run units.
quiet point: A time when no run units are accessing a database. Quiet points and transactions are mutually exclusive (for the entire database). Compare with transaction.
For the run unit, the time between a COMMIT or ROLLBACK, and the
ready mode: The state of a realm after execution of a
READY statement for that realm and before the execution of a COMMIT or
ROLLBACK statement for that realm.
realm: One or more schema areas. Realms are declared
in the subschema. See also area.
realm currency indicator: A currency indicator (in
other words, database key value) associated with a particular realm. A
realm currency indicator identifies a particular database record,
position in the realm, or both.
record key: A key whose contents identify a record in
an indexed file or within a record type in a database. Within an
indexed file, record key is either the prime record key or an alternate
record key. Within a database, a record key may or may not have
record occurrence: A user-stored instance of a record
type. A record occurrence is the actual physical data representation of
a single record in the database, but not its definition, which is the
record order key: A record key associated with a
record type in a database. The definition of a record order key in the
schema causes the DBCS to maintain the records in the specified logical
sequence based on values of the record order key.
record selection expression: A word or group of
contiguous words in a COBOL source program that specifies the algorithm
to be used by the Database Control System (DBCS) to identify a specific
record type currency indicator: A currency indicator
associated with a particular database record type. A record type
currency indicator identifies a particular record of the record type.
If the subschema includes a record order key for a record type, its
associated currency indicator identifies a particular record, position
in the record type, or both.
RETRIEVAL usage mode: The state of a realm in which
the current run-unit may only retrieve from it.
schema: The logical description of a database,
including data definitions and data relationships. The schema is
written using the schema data definition language (schema DDL).
schema DDL: The language used to define the logical
structure of a database.
schema-name: A user-defined word that identifies a
section header: A combination of words (followed by a
separator period) that indicates the beginning of a section in the
Environment, Data, and Procedure Divisions of a COBOL program. In the
Environment and Data Divisions, a section header consists of reserved
words followed by a separator period in the Division. SUB-SCHEMA
SECTION is a valid section header.
set: A defined relationship among records in a
database. A set contains an owner record and zero or more member
records. See also set occurrence , set type, and
set member: A record stored in the database as a
nonowner participant in a specific set.
set-name: A user-defined word that identifies a set
set occurrence: An instance of a database set type. A
set occurrence is the actual data in the set, not its definition, which
is the set type.
set-ordering criteria: The specification for the
positioning of a member record in a set by the DBCS. The schema defines
set owner: A database record occurrence whose
existence establishes the existence of a specific set occurrence.
set type: A specific named set that has been defined
in the schema data definition language. It is the definition of a
collection of sets that have identical characteristics. Set types are
declared by the schema data definition language.
set type currency indicator: A currency indicator
associated with a particular database set type. A set type currency
indicator identifies a particular set of the set type and a particular
record, position in that set, or both.
simple condition: Any single condition from the following list:
simple-condition (in parentheses)
tenancy condition (Oracle CODASYL DBMS simple condition type)
empty condition (Oracle CODASYL DBMS simple condition type)
database key condition (Oracle CODASYL DBMS simple condition type)
singular set: See SYSTEM-owned set.