Indexes

An index is an optionally created database object used primarily to increase query performance. Indexes can also limit the amount of data that is returned in the results without having to retrieve all of data columns of a table. This can help keep results in memory and bring back results faster. The purpose of a database index is similar to that of an index in the back of a book. A book index associates a topic with a page number. When you are locating information in a book, it is usually much faster to examine the index first, find the topic of interest, and identify associated page numbers. With this information you can navigate directly to specific page numbers in the book.