INDEXES
CONTENT
- Definition of Indexes
- Types of Index
- Indexes using Composite Search Keys
Definition of Index
An index serves as a crucial navigational aid in the realm of databases, functioning akin to an index found at the back of a book. Much like the way an index guides readers to specific pages or topics within a book, a database index directs queries to precise physical locations of data within a table.
Types of Index
Clustered vs. Non-Clustered Indexes
In the database landscape, we encounter two prominent types of indexes: Clustered and Non-Clustered indexes.
Clustered Index
A clustered index arranges table data in the same order as the index’s keys. In essence, it physically organizes data on pages, ensuring that rows are stored in key order. This key-ordered storage extends to pages, which are linked in alignment with the key sequence. When dealing with pages-locked tables, the key order becomes especially significant, whereas for data-only-locked tables, indexes guide data storage on rows and pages, albeit without strict key ordering.
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