17.00 - Flow Control - Teradata Workload Management

Teradata Vantageā„¢ - Workload Management User Guide

prodname
Advanced SQL Engine
Teradata Workload Management
vrm_release
17.00
created_date
June 2020
category
Administration
User Guide
featnum
B035-1197-170K

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.