Ordered Indices In an ordered index,index entries are stored sorted on the search key value.E.g.,author catalog in library. Primary index:in a sequentially ordered file,the index whose search key specifies the sequential order of the file. Also called clustering index The search key of a primary index is usually but not necessarily the primary key. Secondary index:an index whose search key specifies an order different from the sequential order of the file.Also called non-clustering index. Index-sequential file:ordered sequential file with a primary index. Database System Concepts-5th Edition,Oct 4,2006 12.5 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 12.5 ©Silberschatz, Korth and Sudarshan th Edition, Oct 4, 2006 Ordered Indices In an ordered index, index entries are stored sorted on the search key value. E.g., author catalog in library. Primary index: in a sequentially ordered file, the index whose search key specifies the sequential order of the file. Also called clustering index The search key of a primary index is usually but not necessarily the primary key. Secondary index: an index whose search key specifies an order different from the sequential order of the file. Also called non-clustering index. Index-sequential file: ordered sequential file with a primary index