17.10 - Flow Control - Advanced SQL Engine - Teradata Workload Management

Teradata Vantageā„¢ - Workload Management User Guide

Product
Advanced SQL Engine
Teradata Workload Management
Release Number
17.10
Release Date
July 2021
Content Type
Administration
User Guide
Publication ID
B035-1197-171K
Language
English (United States)

Flow control means that some tasks cannot send more work to busy AMPs. If many AMPs are in flow control, response times degrade and become inconsistent. This is a more serious situation than simple AWT depletions because request priorities are not honored while messages are being retried.

To define a system Flow Control event, specify the number of AMPs that report flow control during the Qualification period. TASM does not distinguish between being in flow control for 1 msec and being in flow control for the entire interval. Different AMPs can be in flow control during the Qualification period, as long as the # of AMPs criterion is met.