Secondary indexes, Database Management System

Assignment Help:

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


Related Discussions:- Secondary indexes

Describe the relational model, a) Distinguish between ‘database' and ‘Data...

a) Distinguish between ‘database' and ‘Database Management Systems (DBMS)'. b) List and briefly describe five potential benefits of the database approach compared to conventio

Equi join-table handling, Equi Join: A join in which the joining condition...

Equi Join: A join in which the joining condition is based on equality among values in the common columns. Common columns show (redundantly) in the result table. Let us Consider th

Determine the persistent object, Determine the Persistent object Persis...

Determine the Persistent object Persistent object can be stored in one of the following: Files Cheap, permanent, simple storage Low level (Write, Read) Ap

Define the notation for classes and atrributes, Define the notation for cla...

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

For known, What are the function of DBA?

What are the function of DBA?

What are domain constraints, What are domain constraints?  A  domain is...

What are domain constraints?  A  domain is  a  set  of  values  that  might  be  assigned to an attribute  .all  values that appear in a  column of a relation must be taken fro

Management information system, management information system based on funct...

management information system based on functional organisation

Write short note on data models, Write short note on Data models? Data...

Write short note on Data models? Data models: A data model is an abstract model which elaborates how data is represented and accessed. The term data model has two commonly ac

Using sql create a view rs for the relations r and s, Using SQL create a vi...

Using SQL create a view RS for the relations R and S. The view consists of the columns A and D renamed as X and Y in that order. Insert a tuple into it. Show the contents of t

Self-join, Self-Join:   In a self join a table is joined with itself.  Let ...

Self-Join:   In a self join a table is joined with itself.  Let consider the following sample partial data of EMP table EMPNO ENAME MGRID

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd