DBMS: Clustered Index (Definitions)

"An index in which the physical order and the logical (indexed) order is the same. The leaf level of a clustered index represents the data pages themselves." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A clustered index forces the rows in a table to be physically stored in sorted order, using one or more columns from the table to sort the rows. A table may have only one clustered index, such as a dictionary." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An index that the DBMS uses to determine the order of data rows, according to values in one or more columns, called the cluster key. With a strong-clustered index, the data pages are the index's leaves and are thus always in order. With a weak-clustered index, data pages are separate from index leaf pages and the rows need not be 100% in order. The terms weak clustered index and strong-clustered index are not common usage; they appear only in this book." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A clustered index in SQL Server is a type of index in which the logical order of key values determines the actual data rows; thereby the data rows are kept sorted. Using a clustered index causes the actual data rows to move into the leaf level of the index." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"This is an index that physically rearranges the data that is inserted into your tables." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An index whose leaf level is the actual data page of the table." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"An index in which the logical order of the key values determines the physical order of the corresponding rows in a table." (Microsoft, "SQL Server 2012 Glossary", 2012)

"This is an index that contains a table’s row data in its leaf-level nodes." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide" 3rd Ed, 2012)

"An index that contains a table’s row data in its leaf-level nodes." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed, 2015)

"An index whose sequence of key values closely corresponds to the sequence of rows stored in a table. The degree of correspondence is measured by statistics that are used by the optimizer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)