Multi-list file organisation, Database Management System

Multi-list file Organisation

Multi-list file organisation is a multi-index linked file organisation. A linked file organisation is a logical organisation where physical ordering of records is not of concern. In linked organisation the series of records is governed by the links that verify the next record in series. Linking of records can be unordered but such a linking is very costly for searching of information from a file. Thus, it may be a good idea to link records in the order of increasing primary key. This will facilitate deletion and insertion algorithms. Also this really helps the search performance. In addition to making order during linking, search by a file can be further facilitated by producing primary and secondary indexes. All these ideas are supported in the multi-list file organisation. Let us describe these concepts further with the help of an example.

Consider the employee data as given in Figure. The record numbers are given as alphabets for better explanation. Suppose that the Empid is the key field of the data records. Let us describe the Multi-list file organisation for the data file.

 

Record

Number

Empid

Name

Job

Qualification

Gender

City

Married/

Single

Salary

A

800

Jain

Software

Engineer

B. Tech.

Male

New Delhi

Single

15,000/-

B

500

Inder

Software

Manager

B. Tech.

Female

New Delhi

Married

18,000/-

C

900

Rashi

Software

Manager

MCA

Female

Mumbai

Single

16,000/-

D

700

Gurpreet

Software

Engineer

B. Tech.

Male

Mumbai

Married

12,000/-

E

600

Meena

Software

Manager

MCA

Female

Mumbai

Single

13,000/-

                                                                  Figure: Sample data for Employee file

Since, the primary key of the file is Empid, thus the linked order of records should be defined as B (500), E(600), D(700), A(800), C(900). Though, as the file size will grow the search performance of the file would deteriorate. Therefore, we can make a primary index on the file (please note that in this file the records are in the logical series and tied together using links and not physical placement, thus, the primary index will be a linked index file rather than block indexes).

Posted Date: 3/8/2013 6:17:53 AM | Location : United States







Related Discussions:- Multi-list file organisation, Assignment Help, Ask Question on Multi-list file organisation, Get Answer, Expert's Help, Multi-list file organisation Discussions

Write discussion on Multi-list file organisation
Your posts are moderated
Related Questions
Serialisability: Any schedule that makes the similar results as a serial schedule is known as a serialisable schedule. But how can a schedule are determined to be serialisable or n

From SAD to OOAD (Structured Analysis and Design (SAD) to Object Oriented Analysis and Design (OOAD). We will find here how we can map various models in SAD to different model

What is the main difference between read-only and update methods? A read-only method does not affect the values of a variable in an object, whereas an update method may alter t

Question: (a) Discuss the difference between a composite key and a composite attribute. How would each be indicated in an E-R diagram? Support your answer with appropriate exam

Explain Deadlock detection and recovery Deadlock Detection - A deadlock is said to take place when there is a circular chain of transaction, every waiting for the release of a

What is conceptual model ? A conceptual model is a independent of both hardware and software.

Example : Create a sequence named SEQSS that starts at 105, has a step of 1 and can take maximum value as 2000.  CREATE SEQUENCE SEQSS START WITH 105 INCREMENT BY 1 MAX VA

The Database administrator (DBA) uses the data dictionary in each phase of a database life cycle, beginning from the data gathering phase to the design, execution and maintenance p

Ask questApollo Hospitals (AH) is a popular medical service provider in Oman. AH wants to automate its business functions into an information system. The proposed information syst

Views A view is like a window by which data from tables can be changed or viewed. The table on which a view is based is known as Base table. The view is stored as a SELECT stat