Book Image

Microsoft SQL Server 2012 Integration Services: An Expert Cookbook

Book Image

Microsoft SQL Server 2012 Integration Services: An Expert Cookbook

Overview of this book

SQL Server Integration Services (SSIS) is a leading tool in the data warehouse industry - used for performing extraction, transformation, and load operations. This book is aligned with the most common methodology associated with SSIS known as Extract Transform and Load (ETL); ETL is responsible for the extraction of data from several sources, their cleansing, customization, and loading into a central repository normally called Data Warehouse or Data Mart.Microsoft SQL Server 2012 Integration Services: An Expert Cookbook covers all the aspects of SSIS 2012 with lots of real-world scenarios to help readers understand usages of SSIS in every environment. Written by two SQL Server MVPs who have in-depth knowledge of SSIS having worked with it for many years.This book starts by creating simple data transfer packages with wizards and illustrates how to create more complex data transfer packages, troubleshoot packages, make robust SSIS packages, and how to boost the performance of data consolidation with SSIS. It then covers data flow transformations and advanced transformations for data cleansing, fuzzy and term extraction in detail. The book then dives deep into making a dynamic package with the help of expressions and variables, and performance tuning and consideration.
Table of Contents (23 chapters)
Microsoft SQL Server 2012 Integration Services: An Expert Cookbook
Credits
Foreword
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Data Flow best practices in Extract and Load


When we extract data from sources, the main focus is on getting just the changed data (inserts, updates, and deletes) since our last extraction. Reading all data (that could be millions of rows) from sources and then making a comparison row-by-row could cause a bottleneck in the system.

To get just the required data, several techniques can be applied:

  • Audit columns: Having a date and time column for changes or even having two columns, one for insert and another for the update of a specific record.

  • Checksums: Using an algorithm to create a unique identifier for a column set. Microsoft included in SQL 2008 a new SQL function that enables this technique to be applied faster and more easily.

  • Change Data Capture (CDC): Save logs from changes in a specific table using a higher performance approach than using triggers. This is a new functionality included in the SQL 2008 engine and now included in SSIS 2012 with a new task and two components.

Several other...