Introduction to Data Management

Glossary
Glossary-2 15873 Tandem Computers Incorporated
Autorollback. A rapid recovery mechanism provided by TMF that enables a database to
recover from a computer system failure. After the system is restored to operation, the
autorollback facility uses TMF audit trails to automatically return the database to its
most consistent state following the failure.
Backout. A mechanism provided by TMF that protects a database from the effects of
individual transaction failures. When a transaction aborts while in progress, TMF
backs out (withdraws or cancels) the database changes imposed up to that point,
restoring the database to the state it was in prior to the start of the transaction. The
backout process ensures that either all changes requested by a transaction are
imposed, or that none of them are.
Backup database. A logical replication of the primary database, created and maintained
by RDF at a backup system. The backup database can replace the primary database in
case of a disaster.
Backup system. The system that supports a backup database maintained by RDF.
Before-image. A copy or copied portion of a database record that is made by TMF
before a transaction changes the record.
Catalog. In NonStop SQL, a set of tables containing the descriptions of SQL objects
such as tables, views, columns, indexes, files, and partitions. In PATHMAKER, a set
of files in which PATHMAKER maintains information about a specific ongoing
project.
Catalog table. In NonStop SQL, one of the tables in a catalog; each table describes
objects such as tables, columns, views, and indexes.
COBOL 74. The Tandem compiler and run-time support for the American National
Standard Programming Language COBOL, X3.23-1974.
COBOL85. The Tandem compiler and run-time support for the American National
Standard Programming Language COBOL, X3.23-1985.
Column. A collection of items (different values of the same field) in a relational
database; a vertical component of a table. A column contains one data value for each
row of the table; the column is the relational equivalent of a set of fields.
Command terminal. See PATHWAY command terminal.
Commit record. A record in a TMF audit trail that identifies a committed transaction
made permanent in the database.
Committed transaction. A transaction that has successfully completed all of its changes
to the database.
Concurrency control. Protection of a database record from concurrent access by more
than one process. TMF imposes this control by dynamically locking and unlocking
affected records to ensure that only one transaction at a time accesses those records.