Skew Exception Criteria | Teradata Vantage - Skew Exception Criteria - Analytics Database - Teradata Workload Management

Teradata Vantageā„¢ - Workload Management User Guide - 17.20

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Workload Management
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2023-01-27
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B035-1197
Product Category
Teradata Vantage

A skewed request can severely impact the parallel efficiency of the system, eliminating the benefit of multiple AMPs. If the system is processing one skewed request step, all the AMPs with less processing to do must wait until the single skewed AMP with more processing to do completes. Only the skewed AMP runs at capacity while the other AMPs sit idle. In a mixed workload, the skewed AMP cannot respond as quickly as the other AMPs because it is clogged with skewed processing. All requests in the system can slow down when there is a skew.