Oracle 9i Fundamentals I Exam Cram™ 2 (Exam 1Z0-031)

Creating Indexes

Indexes are created either in the account of the user who owns the table on which they are built, or in a different account. It is generally the practice to create all indexes in the table owner's account.

There are several things to consider when you are deciding whether to create an index. This section discusses many of these considerations.

Criteria for Creating an Index

You will likely want to create an index if you have queries that frequently retrieve less than roughly 15% of the rows in a large table. The percentage naturally varies somewhat according to the relative speed of a full table scan on that table and that column and on exactly how clustered the row data is in relationship to the index key. The faster the table ...