17.00 - Tuning the Pack Factor - Parallel Transporter

Teradata® Parallel Transporter Application Programming Interface Programmer Guide

prodname
Parallel Transporter
vrm_release
17.00
created_date
June 2020
category
Programming Reference
featnum
B035-2516-220K

Packing multiple-statement requests improves network/channel efficiency by reducing the number of sends and receives between the application and the database.

To determine the ideal pack factor to specify in the Pack attribute, first use the PackMaximum attribute by setting it to Yes. Setting this attribute to Yes on the first job run sets up iterative interactions with the database to heuristically determine the maximum possible pack factor.

At the end of the run, this value is displayed in the logged output for the Stream driver. The value determined should then be specified in the Pack attribute on subsequent runs and PackMaximum should be set to No.

Alternatively, query the TD_Evt_PackFactor event after initiating a connection and before terminating it to retrieve the pack factor currently in use.

When the following conditions are met:
  • The schema has variable-length columns and
  • Array Support is on and
  • One of the following:
    • The PACK factor is set to 2400
    • The PACKMAXIMUM is set to 'Y[es]'
    • Neither the PACK factor attribute nor PACKMAXIMUM attribute is populated

You will be informed of the "floating" Pack factor in a message similar to the following:

**** 14:50:34 The PACK factor has changed. The minimum PACK factor is about 1270 data records per request. The maximum PACK factor is about 1298 data records per request.

In the message above, the word "about" indicates that slave instances can have a different Pack factor.