16.10 - System-Derived and System-Generated Columns - Teradata Database

Teradata Database SQL Fundamentals

Teradata Database
Release Number
June 2017
English (United States)
Last Update

In addition to the table columns that you define, tables contain columns that Teradata Database generates or derives dynamically.

Column Description
Identity A column that was specified with the GENERATED ALWAYS AS IDENTITY or GENERATED BY DEFAULT AS IDENTITY option in the table definition.
Object Identifier (OID) For a table that has LOB columns, OID columns store pointers to subtables that store the actual LOB data.
PARTITION For a table that is defined with a partitioned primary index (PPI), the PARTITION column provides the partition number of the combined partitioning expression associated with a row, where the combined partitioning expression is derived from the partitioning expressions defined for each level of the PPI. This is zero for a table that does not have a PPI.
PARTITION#L1 through PARTITION#L62 For tables that are defined with a multilevel PPI, these columns provide the partition number associated with the corresponding level. These are zero for a table that does not have a PPI and zero if the level is greater than the number of partitions.
ROWID Contains the row identifier value that uniquely identifies the row.

Restrictions apply to using the system-derived and system-generated columns in SQL statements. For example, you can use the keywords PARTITION and PARTITION#L1 through PARTITION#L15 in a query where a table column can be referenced, but you can only use the keyword ROWID in a CREATE JOIN INDEX statement.