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

Explain before executing queries


Teradata gives you the benefit of checking the actual execution plan before executing the query. The English translation of the plan the Teradata optimizer develops to service the SQL. The terms execution plan and explain plan can be used interchangeably:

DIAGNOSTIC VERBOSEEXPLAIN ON FOR SESSION;
DIAGNOSTIC HELPSTATS ON FOR SESSION;

VERBOSEEXPLAIN adds information on the hash fields used to build intermediate spool files. This can be of significant value when diagnosing skewed redistribution.  

HELPSTATS adds a list of RECOMMENDED STATISTICS to the end of the explain plan.  A word of caution: do not blindly collect stats from this list of recommendations. The recommendation usually covers all joining columns with single as well as multi-column options and it may prove costly to collect them. 

Getting ready

You can check the explain plan in SQLA or using Studio Express. The explain plan can also be generated in BTEQ but it would not be easy to read it. Explain...