Sample External Data with a Foreign Table | NOS | Teradata Vantage - 17.10 - Sampling External Data In Place Using a Foreign Table - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - Native Object Store Getting Started Guide

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1214-171K
Language
English (United States)

Preview random rows of data in place from external object store using a foreign table.

The examples use a sample river flow data set. To use your own data, replace the table and column names, and authorization object. See Variable Substitutions for Examples for the credentials and location values for the sample data set.

  1. To run NOS-related commands, log on to the database as a user with the required privileges.
  2. If it does not exist, create the foreign table or ask your database administrator to create the foreign table. See Setting Up to Run Examples.
  3. To see sample records with the attribute names included before each string of values, issue the following command against the foreign table:
    SELECT TOP 2 *
    FROM table_name;
    If you run this on JSON data, the results look different because you get a payload. Inside the payload field, you get a comma delimited list of values.

    On CSV and Parquet, you get a list of columns with data.

Example: Sampling External Data In Place Using a Foreign Table

If not already done, create the foreign table. See Setting Up to Run Examples.

SELECT TOP 2 *
FROM riverflow;

Your results will be similar to the following:

    Location /S3/s3.amazonaws.com/td-usgs-public/CSVDATA/09400815/2018/07/10.csv
  GageHeight2     ?
         Flow   .00
      site_no     9400815
     datetime 2018-07-10 00:00
Precipitation   .00
   GageHeight  -.01

     Location /S3/s3.amazonaws.com/td-usgs-public/CSVDATA/09400815/2018/07/12.csv
  GageHeight2     ?
         Flow   .00
      site_no     9400815
     datetime 2018-07-12 00:00
Precipitation   .00
   GageHeight  -.01

The output is displayed vertically for readability.