Before you start
Thinking about seeking certification on DB2 fundamentals (Exam 730)? If so, you've landed in the right spot. This series of seven DB2 certification preparation tutorials covers all the basics -- the topics you'll need to understand before you read the first exam question. Even if you're not planning to seek certification right away, this set of tutorials is a great place to start getting to learn what's new in DB2 9.
This tutorial will introduce you to the concept of data consistency and to the various mechanisms that are used by DB2 for Linux, UNIX, and Windows to maintain data consistency in both single- and multi-user database environments. In this tutorial, you will learn:
- What data consistency is
- What transactions are and how they are initiated and terminated
- How transactions are isolated from each other in a multi-user environment
- How DB2 for Linux, UNIX, and Windows provides concurrency control through the use of locks
- What types of locks are available and how locks are acquired
- What factors influence locking
This tutorial is the sixth in a series of six tutorials that you can use to help prepare for the DB2 9 Fundamentals (Exam 730). The material in this tutorial primarily covers the objectives in Section 6 of the exam, entitled "Data Concurrency." You can view these objectives at: http://www.ibm.com/certify/tests/obj730.shtml.
You do not need a copy of DB2 for Linux, UNIX, and Windows to complete this tutorial. However, you can download a free trial version of DB2 for Linux, UNIX, and Windows Enterprise Edition.
After completing this tutorial, you should be able to:
- Identify factors that influence locking
- List objects on which locks can be obtained
- Identify characteristics of DB2 locks
- Identify the isolation level that should be used for a given situation
In order to understand some of the material presented in this tutorial, you should be familiar with the following terms:
Object: Anything in a database that can be created or manipulated with SQL (e.g., tables, views, indexes, packages).
Table: A logical structure that is used to present data as a collection of unordered rows with a fixed number of columns. Each column contains a set of values, each value of the same data type (or a subtype of the column's data type); the definitions of the columns make up the table structure, and the rows contain the actual table data.
Record: The storage representation of a row in a table.
Field: The storage representation of a column in a table.
Value: A specific data item that can be found at each intersection of a row and column in a database table.
Structured Query Language (SQL): A standardized language used to define objects and manipulate data in a relational database. (For more on SQL, see the fourth tutorial in this series.
DB2 optimizer: A component of the SQL precompiler that chooses an access plan for a Data Manipulation Language (DML) SQL statement by modeling the execution cost of several alternative access plans and choosing the one with the minimal estimated cost.
You do not need a copy of DB2 to complete this tutorial. However, you will get more out of the tutorial if you download the free trial version of IBM DB2 for Linux, UNIX, and Windows to work along with this tutorial.