Book Image

Teradata Cookbook

By : Abhinav Khandelwal, Viswanath Kasi, Rajsekhar Bhamidipati
Book Image

Teradata Cookbook

By: Abhinav Khandelwal, Viswanath Kasi, Rajsekhar Bhamidipati

Overview of this book

Teradata is an enterprise software company that develops and sells its eponymous relational database management system (RDBMS), which is considered to be a leading data warehousing solutions and provides data management solutions for analytics. This book will help you get all the practical information you need for the creation and implementation of your data warehousing solution using Teradata. The book begins with recipes on quickly setting up a development environment so you can work with different types of data structuring and manipulation function. You will tackle all problems related to efficient querying, stored procedure searching, and navigation techniques. Additionally, you’ll master various administrative tasks such as user and security management, workload management, high availability, performance tuning, and monitoring. This book is designed to take you through the best practices of performing the real daily tasks of a Teradata DBA, and will help you tackle any problem you might encounter in the process.
Table of Contents (19 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Index

Improving update performance


An update is a data manipulation language, or DML operator. Updating a PI column causes performance degradation:

UPDATE table_name SET col_name=expression [, ..., col_name=expression]
[ALL | WHERE condition];

Getting ready

For this recipe to complete, you need to connect to the Teradata instance and open SQLA.

How to do it...

  1. Identify the target table that needs to be updated.
  2. Identify the source table from which the update is to be done:
update test01.web_clicks a -- Target update table
from test02.wed_address b -- Source update table
set acc_last_date= date -- Target column that's need to updated
where a.Rego_Start_Dt between '2016-12-25' and '2017-01-28' -- Partition column

How it works...

As we understand it, update is used to alter or change the values of existing rows of a table. The updating of the rows can be based on some where condition or full table if needed. You can use sub queries in update statements.

There is much to consider when it comes to updating rows...