Database Task Concurrency Limits - Parallel Transporter

Teradata® Parallel Transporter User Guide - 17.20

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
Lake
VMware
Product
Parallel Transporter
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2023-08-25
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B035-2445
Product Category
Teradata Tools and Utilities
To ensure that the data remains accessible to users, the database enforces limits on the quantity of system resources that can be used by extract and load utilities. These limits affect use of the following operators:
  • Export
  • Load
  • Update
Each time one of these operators is referenced in an APPLY statement counts as one task. Limits are controlled by two DBSControl settings:
  • MaxLoadAWT
  • MaxLoadTasks

The system counts the total number of tasks attempting to run concurrently and then the settings of the two fields are applied to that total, and task limits are enforced, where necessary.

To get a general idea of total concurrent Teradata PT tasks for your site, consider the following basic rules:
  • Each operator specified in an APPLY statement that interfaces with the database constitutes one task. For example:
    • A job that moves data between a database and either a second, separate database or an external source or target requires only one task, because only a single operator interfaces with each database at one time.
    • A job that moves data within a single database requires two tasks, because both the extract and load operators interface with the database at the same time.

      Keep in mind that job steps within a single job execute sequentially, so the maximum number of concurrent tasks in a single job is two.

  • If more than one job script is running concurrently, the total number of tasks applied to the MaxLoad calculations is based on the total number of operators that run concurrently in all jobs.
  • Default MaxLoad settings allow concurrent execution of approximately 15 tasks, so you may need to reset the MaxLoad values.

Actual limits are subject to additional factors. For details on how to set the MaxLoadAWT and MaxLoadTasks fields in the DBSControl GDO, and how those settings will affect Teradata PT jobs, see "DBSControl utility" in Teradata Vantage™ - Database Utilities, B035-1102.