Schemas

A schema is a set of metadata definitions about the columns and rows of a data source or destination object, such as:

Data types and column sizes

Precision, scale, and null-value indicators

Database tables, columns and rows

Teradata PT uses schema definitions, which are similar to SQL table definitions. The schema definitions used in Teradata PT:

Represent virtual tables. They do not have to correspond to any actual tables in the Teradata Database.

Contain column definitions: names, and data types.

Act as reusable templates

Describe the contents of various data sources and targets, such as files, relational tables, etc.

Are similar to record layout definitions used by the Teradata standalone load and unload utilities.

An example of a schema definition follows:

DEFINE SCHEMA FREQ_FLYER_SRC

DESCRIPTION ‘SCHEMA FOR FREQUENT FLYER SOURCE FILE’

     RES_ID                VARCHAR(14),

     FLIGHT_NO             SMALLINT,

     ORIGIN                CHAR(3),

     DEST                  CHAR(3),

     TKT_ID                CHAR(12)

     TKT_ISSUE_DATE        ANSIDATE,

     TKT_AMT               DECIMAL(5,2),

     TRAVEL_AGCY_ID        CHAR(4),

     FREQ_MILES_ID         CHAR(8)

);