Example: Creating and Using an EXTERNAL SECURITY Clause in a UDF - Advanced SQL Engine - Teradata Database

SQL Data Definition Language Syntax and Examples

Product
Advanced SQL Engine
Teradata Database
Release Number
17.00
Published
September 2020
Language
English (United States)
Last Update
2021-01-23
dita:mapPath
wgr1555383704548.ditamap
dita:ditavalPath
lze1555437562152.ditaval
dita:id
B035-1144
lifecycle
previous
Product Category
Teradata Vantage™

Suppose you have defined the following external authorization object:

     CREATE AUTHORIZATION DEFINER sales
     USER 'salesdept'
     PASSWORD 'secret';

You now create the following C UDF:

     CREATE FUNCTION sales_collect (
       store_number INTEGER, 
       item_no      INTEGER)
     RETURNS INTEGER
     LANGUAGE C
     NO SQL
     EXTERNAL 'cs!salecol!salecollector.c'
     PARAMETER STYLE SQL
     EXTERNAL SECURITY DEFINER sales;

This function collects data associated with sales for a given store for a given item number (item_no) and returns the number of items sold. One possible, albeit contrived, scenario would have the function communicating with the store via a network interface. The function is created using the DEFINER context. This means that when a user logs onto its database account and executes an SQL request that invokes this function, it uses the logon ID associated with the sales authorization object, not the user that is executing the invoking SQL request. In this example, OS user salesdept has access to the external data the function reads to obtain the information it needs.