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failure Any condition that precludes complete processing of a F Teradata SQL statement. Any failure will abort the current
fallback The ability of the Teradata RDBMS to maintain an extra copy of every row of a table in different AMPs. During normal processing, reads are performed using only the primary copy, while updates are performed on both copies. If a failure renders the primary copy inaccessible, the fallback copy is used for reads and updates. The database maintains a log of changes missed by inaccessible copies and automatically applies the missed changes to synchronize the table copy when it becomes accessible.
field The basic unit of information stored in the Teradata RDBMS. A field is either null, or has a single numeric or string value. See also column, database, row, table.
firmware Programming that is permanently fixed into a subsystem, as opposed to a software system, which is replaced without altering a hardware configuration.
foreign key An attribute of one table whose values are required to match those of the primary key of some other table.
Gateway A program on the server that provides a pathway for G applications running on a network-connected client to access the
Teradata RDBMS. Cf: channel connection software.
hashing A way of mapping data records to various physical storage areas. In the Teradata RDBMS, hashing is used to determine at which AMP a given row will be stored.
hierarchical An organization of entities, such as data records, in which some “superior” or “parent” entities are related to one or more “subordinate” or “child” entities. Also pertains to any
Introduction to the Teradata RDBMS for UNIX
database management system that uses or describes information in a hierarchical form, such as IMS/VS. Cf: inverted, network, relational.
host A general-purpose computer that can execute application programs that access and manipulate information within the Teradata RDBMS.
host-resident Pertaining to a system or application program that executes on a host computer.
Host System Communication Interface. See HSCI.
host utility program One of several programs that executes on the mainframe host computer to archive data from the Teradata RDBMS to tape and/or to restore archived data to the Teradata RDBMS, and to load data to the Teradata RDBMS from a host input file.
HSCI The Host System Communication Interface, which consists of the Teradata Director Program, Call-Level Interface, and user-to-TDP communication techniques. These HSCI components enable communication between the user-written and Teradata application programs and the Teradata RDBMS.
index In Teradata SQL, a means of ordering and locating rows on disk for efficient access and processing. Cf: primary index, secondary index, unique.
inverted A form or organization of records in a Database Management System in which extensive use is made of secondary index capability to access alternative paths to records. Each secondary index is also known as an “inversion.” Cf: hierarchical, network, relational.
join In Teradata SQL, a select operation that combines information from two or more tables to produce a result.
key The value(s) of the index field(s) that locates a row within a user
K database running under the Teradata RDBMS.
keyword A string of characters that has a special meaning in the Teradata SQL. A keyword cannot be used as a name.
LAN See Local Area Network.
Local Area Network (LAN) A means of connecting workstations that allows them to communicate with one another. The LAN is usually confined to a limited area, such as a building.
lock In Teradata SQL, the right to use a database, table, or row for a particular purpose (such as to read or write) with the assurance that other activities in the system cannot alter the object in a way that
Introduction to the Teradata RDBMS for UNIX
could affect the outcome of the activity that holds the lock. Users who do not require data consistency may use a lock specifically for access.
logical Pertaining to an entity, record, or grouping of data that is treated as a unit by a software program, as opposed to an entity that is treated as a unit by hardware.
macro A set of Teradata SQL statements stored by the Teradata RDBMS and executed by a single EXECUTE statement. Each macro execution is implicitly treated as a transaction.
mainframe A large computer with extensive capabilities and resources to which other computers can be connected so they can share facilities.
message The basic unit of information interchange between an application program and the Teradata RDBMS. An application program sends messages via a session to the Teradata RDBMS in halfduplex fashion and must wait for a response message from the Teradata RDBMS before sending another message on the same session. Messages consist of one or more parcels, which are logical subdivisions of a message.