Advantages of Row Triggers
The most common use of row triggers is with OLD and NEW correlation names that reference current row values as scalar quantities. The following bullets describe the advantages of row triggers:
If the triggered action for a row changes data values in such a way that the WHEN condition search results for some rows might be affected, then the system must wait for completion of the triggered action before proceeding to the next row. A trigger with such characteristics cannot take full advantage of the Teradata parallel architecture.