Contents Index Indexes Improving index performance

ASA SQL User's Guide
  Query Optimization and Execution
    Indexes

When to create an index


There is no simple formula to determine whether or not an index should be created for a particular column. You must consider the tradeoff of the benefits of indexed retrieval versus the maintenance overhead of that index. The following factors may help to determine whether you should create an index.

The Index Consultant is a tool that assists you in the selection of an appropriate set of indexes for your database. For more information, see Index Consultant overview.

Temporary tables 

You can create indexes on both local and global temporary tables. You may want to consider indexing a temporary table if you expect it will be large and accessed several times in sorted order or in a join. Otherwise, any improvement in performance for queries is likely to be outweighed by the cost of creating and dropping the index.

For more information, see Working with indexes.


Contents Index Indexes Improving index performance