1.1 - 8.10 - RowDistribution Function (ML Engine) - Teradata Vantage

Teradata Vantage™ - Machine Learning Engine Analytic Function Reference

Product
Teradata Vantage
Release Number
1.1
8.10
Published
October 2019
Content Type
Programming Reference
Publication ID
B700-4003-079K
Language
English (United States)

The primary purpose of the RowDistribution function is to examine the distribution of data across vworkers. Skewed data distribution can decrease the performance (calculation speed) of some analytic functions. For more information, and instructions for interpreting the results of this function, see Determining if Data Skew Might Impact Performance.

Another use of the RowDistribution function is to get the configuration (number of worker nodes and vworkers) of the ML Engine cluster.

RowDistribution Syntax

SELECT * FROM RowDistribution (
    ON { table | view | (query) } 
) AS alias;

RowDistribution Input

The input table can have any schema.

RowDistribution Output

RowDistribution Output Table Schema
Column Data Type Description
task_index INTEGER Identifier of vworker.
ip_address CLOB IP address of worker node containing vworker.
row_count BIGINT Number of input table rows stored on vworker.

RowDistribution Example

Input: housing_train, as in GLM Example: Gaussian Distribution Analysis

SQL Call:

SELECT * FROM RowDistribution (
    ON housing_train 
) AS dt;

Output:

 task_index |  ip_address  | row_count 
------------+--------------+-----------
          0 | 10.25.17.133 |       162
          2 | 10.25.17.131 |       163
          1 | 10.25.17.129 |       167
(3 rows)