One of the most important tasks for every database administrator (DBA) is to ensure that query times are consistent with service-level agreement (SLAs) or within user expectations. One of the most effective techniques to achieve this objective is to create indexes on tables for your queries. SQL Server uses indexes to sort and organize table data. It creates indexes based on ordering values from one or more selected columns. SQL Server automatically creates indexes when you define a primary key or unique constraint. You can use indexes to manage and track rows in a table or an indexed view.
Indexes improve the performance on most data scans by reducing the overall time query takes to run and the amount of work and resources it consumes. The amount of performance improvement depends on the size of the tables involved, the index design, and the type of query. You can see the role of indexes by observing what happens during queries and data manipulation.
Checkout the part-1 of my five part article series on Guide to SQL Server Table Indexes here, in which you’ll learn about the basics of SQL Server database table’s indexes, the difference between the clustered and non-clustered indexes, and how the leaf nodes, non-leaf nodes, and heaps associated with data storage.
This article is published on SQL-SERVER-PERFORMANCE.COM.