Default Sessions and Streams | Teradata Data Mover - 17.11 - Default Sessions and Streams - Teradata Data Mover

Teradata® Data Mover User Guide

Product
Teradata Data Mover
Release Number
17.11
Release Date
October 2021
Content Type
User Guide
Publication ID
B035-4101-091K
Language
English (United States)

Data Mover dynamically determines the number of source or target sessions and streams if you do not specify a value for source_sessions, target_sessions or data_streams. This determination is based on several factors, including the number of AMPs, number of AMPs in a map (if supporting the Teradata Database MAPS Architecture feature), size of objects being moved, and so forth. These dynamic values provide a good starting point if you are not familiar with tuning utilities to maximize performance. It is recommended that users test various combinations, as the ideal setting for each job will vary from site to site. In cases where a specific value better suits the requirements for a particular job, you can specify the value for source_sessions, or target_sessions, or data_streams.

The status output displays the number of source and target sessions or streams used to move each object.

For DSA jobs, source_sessions and target_sessions do not apply. DSA auto-determines the number of soft streams when data_streams is not specified. To limit the number of soft streams used during data transfer, specify a smaller data_streams value.

For TPT jobs, the number of sessions and streams is calculated for each object being moved. Every object being moved uses a different combination of the source and target sessions and data streams for optimal performance. If the source or target system supports MAPS, then the dynamic container or user job inputs for data streams and sessions must follow the following criteria:
  • The source sessions cannot be greater than the AMP count in the source object map.
  • The target sessions cannot be greater than the AMP count in the target object map.
  • The data streams cannot be greater than the AMP count in the source or target object maps.

If the user provides a value for one or more of the three performance settings (source_sessions, or target_sessions, or data_streams), the unspecified values are automatically computed to work best with the user-specified values.

Run the list_job_steps command to view the sessions and streams that were dynamically computed by Data Mover.

If Teradata Active System Management (TASM) session rules are enabled on a particular source or target system, the TASM rules may override the Data Mover sessions.