DML Statement - Parallel Transporter

Teradata Parallel Transporter Reference

Product
Parallel Transporter
Release Number
15.10
Language
English (United States)
Last Update
2018-10-07
dita:id
B035-2436
lifecycle
previous
Product Category
Teradata Tools and Utilities

DML Statement

Using Database Macros

The Stream operator uses macros to modify tables rather than actual DML statements. Before beginning a load, the operator creates macros to represent the DML statements. The macros are then iteratively executed in place of the DML statements. The Stream operator also removes the macros after all rows are loaded.

These actions are accomplished through the use of CREATE/DROP MACRO SQL statements.

Use the MacroDatabase attribute to specify the database that contains the macros created by the Stream operator. If not specified, the database used is the database that contains the Restart Log table.

Multiple Statement Requests

The Stream operator sends conventional CLIv2 parcels to the Teradata Database that are immediately applied to the target table(s). To improve efficiency, the Stream operator builds multiple statement requests and may also employ a serialize mechanism to help reduce locking overhead.

The most important technique used by the Stream operator to improve performance is the multiple statement request. Placing more statements in a single request is beneficial for two reasons. It reduces:

  • Network overhead because large messages are more efficient than small ones.
  • Robust mode recovery overhead to one extra restart log table row for each request.
  • The Stream operator packs multiple statements into a request based upon the Pack attribute specification.