Indexed (indexed sequential) file organisation, Database Management System

Indexed (Indexed Sequential) File Organisation

It organises the file like a big dictionary, i.e., records are kept in order of the key but an index is stored which also allows a type of direct access. The records are kept sequentially by primary key values and there is an index built over the primary key field.

The retrieval of a data from a sequential file, on average, needs access to half the records in the file, making such inquiries not only useless but very time consuming for big files. To improve the query response time of a sequential file, a type of indexing method can be added.

An index is a set of address pairs, index value. Indexing associates a set of objects to a set of orderable quantities, which are generally smaller in number or their properties. Therefore, an index is a mechanism for faster search. While the indices and the data blocks are stored together physically, they are logically distinct. Let us use the word an index file to defines the indexes and let us refer to data files as data records. An index can be small sufficient to be read into the main memory.

A sequential file that is indexed on its primary key is known as an index sequential file. The index permits for random access to records, as the sequential storage of the records of the file gives easy access to the sequential records. An additional feature of this file system is the over flow area. The overflow area gives additional space for record addition without the need to make.



Posted Date: 3/7/2013 6:17:04 AM | Location : United States

Related Discussions:- Indexed (indexed sequential) file organisation, Assignment Help, Ask Question on Indexed (indexed sequential) file organisation, Get Answer, Expert's Help, Indexed (indexed sequential) file organisation Discussions

Write discussion on Indexed (indexed sequential) file organisation
Your posts are moderated
Related Questions
1. Identify the comparisons and exchanges made to sort the following array using the selection exchange sort technique. Note: you may not need all columns. Ori

What is the main advantage of the object model? What are its different components? The object model focuses on the logical data structures. Each object model comprises of many

Project Description: This is a Customer Management project. Customer data is presented in a text file. The program can load this text data into its database columns. The data ma

There are three main sources of utilities and applications for a DBMS: a. Vendor applications and utilities are given for working with or maintaining the database, and generally

What is DataWarehousing? Subject-oriented, meaning that the data in the database is organized so that all the data elements relating to the similar real-world event or object

Explain about primary key Primary Key: It is one of the candidate keys that are taken to be the recognizing key for the entire table. E.g. although there are two candidate ke

Illustrate about the advanced object design Advanced object design is a complex task. The objects discovered through analysis serve as a skeleton of design. The operations reco

What is Data Storage? The storage structures and access methods used by database system are specified by a set of explanation in a special type of DDL called data storage-defin

Explain different categories of failures that occur in Oracle database? Categories of Failures - In Oracle database subsequent types of failures can occurred: Statement Failu

Home based assignment Consider an ORDER table with the following attributes: • Order Number (ONo),Customer Number (CNo),Customer Name (CNa),Item Number (INo),Unit Price (UP), Quant