Information Technology

Expert Indexing in Oracle Database 11g

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An index is an optionally created database object used primarily to increase query performance. The purpose of a database index is similar to an index in the back of a book. A book index associates a topic with a page number. When you’re locating information in a book, it’s 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. If the topic only appears on a few pages within the book, then the number of pages to read is minimal. In this manner, the usefulness of the index decreases with an increase in the number of times a topic appears in a book. Similar to a book index, a database index stores the column value of interest along with its row identifier (ROWID). The ROWID contains the physical location of the table row on disk that stores the column value. With the ROWID in hand, Oracle can efficiently retrieve table data with a minimum of disk reads. In this way, indexes function like a shortcut to the table data. If there is no available index, then Oracle reads each row in the table to determine if the row contains the desired information.

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Detail Information

Series Title

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Call Number

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Publisher

: ., 2012

Collation

1-265

Language

English

ISBN/ISSN

978-1-4302-3736-5

Classification

NONE

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Edition

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Subject(s)

Expert Indexing in Oracle Database 11g

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