Technical data

empty set
A database set occurrence containing no member records.
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.
Glossary–5