Expert Indexing in Oracle Database 11g: Maximum Performance for Your Database

Understanding How Oracle Uses B-tree Indexes

This section will help you understand how Oracle uses B-tree indexes. The goal is to help you fully comprehend B-tree index internals to enable intelligent indexing decisions when building database applications. An example with a good diagram will help illustrate the mechanics of a B-tree index. Even if you've been working with B-tree indexes for quite a while, this example may illuminate technical aspects of using an index. To get started, suppose you have a table created as follows:

create table cust(  cust_id number ,last_name varchar2(30) ,first_name varchar2(30));

You also anticipate that queries will frequently execute against the table using the LAST_NAME column. Therefore, you create a B-tree ...