Secondary indexes, Database Management System

Secondary Indexes

Let consider the student database and its clustering index and primary (only one will be applicable at a time). Now consider the state when the database is to be searched or accessed in the alphabetical order of names. Any search on a student name would need sequential data file search, therefore, is going to be very time consuming. Such a search on an average would need reading of half of the total number of blocks.

Therefore, we require secondary indices in database systems. A secondary index is files that have records having a secondary index field value which is not the ordering field of the data file, and a pointer to the block that have the data record. Please note that even if a data file can have only single primary index (as there can be only single ordering of a database file), it can have many secondary indices.

Secondary index can be described on an alternate key or non-key attributes. A secondary index that is described on the alternate key will be dense as secondary index on non-key attributes would need a bucket of pointers for one index entry. Let us define them in more detail with the help of Figures.

                        828_Secondary Indexes.png

Posted Date: 3/7/2013 6:31:01 AM | Location : United States







Related Discussions:- Secondary indexes, Assignment Help, Ask Question on Secondary indexes, Get Answer, Expert's Help, Secondary indexes Discussions

Write discussion on Secondary indexes
Your posts are moderated
Related Questions
Explain group By clause in SQL? Group By clause in SQL: The GROUP BY clause can be used in a SELECT statement to collect data across multiple records and group the results thro

The Database MySQL scripts cars_for_sale.sql and car_details.sql containing the data to use for this task have been supplied. To complete this task, you need to first create

Define the notation for classes and atrributes The notation for class, attribute, and operations are shown below:     Figure: Class with attributes and operations A

sir, could anybody help me in getting complete information about the mentioned topic

Create a table according to given data:  AmbulanceDriver(Driver_Number#, Name, Address, Birth_Date) AmbulanceDriverTeam(Team_Number#, Driver_Number#, Join_Date, Lea

Explain hash file organization? Hash functions a) The distribution is uniform Hash functions assign each bucket the similar number of search -key values from the set of a


After the completion of the logical model the physical model is to be made. The oracle 10 G will be used as a database server and all the tables with their column are created and i

Discuss the problem of Spurious tuples and how we may prevent it.    Ans:  A spurious tuple is, mainly, a record in a database that gets created while two tables are joined bad

Describe the storage structure of indexed sequential files and their access method. Ans: Index offers a lookup capability to rapidly reach the vicinity of the desired record.