Describe the storage structure of indexed sequential file, Database Management System

Assignment Help:

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.  

  • consists of key field and a pointer to the main file
  • Indexed is searched to find out highest key value that is equal to or precedes the desired key value
  • Search carries on in the main file at the location pointed out by the pointer.

If an index consists of 1000 entries, it will take on average 500 accesses to find out the key, followed by 500 accesses in the main file.  Now on average it is 1000 accesses.

a)      New records are added to an overflow file 

b)      Record in main file which precedes it is updated to include a pointer to the new record 

c)       The overflow is merged along with the main file during a batch update 

d)      Multiple indexes for similar key field can be set up to increase efficiency.

 ISAM that is Indexed Sequential Access Method is a file management system developed at IBM that permits records to be accessed either sequentially (in the order they were entered) or randomly (with an index). Every index defines a different ordering of the records. An employee database may have various indexes, based on the information being sought. For instance, a name index may order employees alphabetically by last name, when a department index may order employees by their department. A key is fixed in each index. For an alphabetical index of employee names, the last name field would be the key.


Related Discussions:- Describe the storage structure of indexed sequential file

Cartisian product, Explain the cartesian product in Database Management Sys...

Explain the cartesian product in Database Management System

What is use of generating such tables, What is use of generating such table...

What is use of generating such tables? How can you create temporary tables? When you require a table only for a short time after that you want it to disappear automatically you

Confirming.., I just purchased a document for you guys and wanted to confir...

I just purchased a document for you guys and wanted to confirm that it will be send within an hour or 2 to my email or where will document be sent to?

Determine object representation, Determine object representation As a ...

Determine object representation As a designer, we must choose properly that when to use primitive types in representing objects and when to combine groups of related objects,

Nested query, what is correlation in nested query

what is correlation in nested query

Sources of utilities for a dbms, There are three main sources of utilities ...

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

Explain query execution plan, Explain query execution plan? - Optimizer...

Explain query execution plan? - Optimizer available in SQL Server optimizes code to be effectively executed. - A query execution plan demonstrates how this optimizer would r

What are the drawbacks of shadow-paging technique, What are the drawbacks o...

What are the drawbacks of shadow-paging technique? The drawbacks of shadow paging is:- a) Commit Overhead b) Data fragmentation c)  Garbage collection

What is an operand, What is an Operand? The data on which the operation...

What is an Operand? The data on which the operation is to be performed is known as an Operand

Explain the term- data flows, Explain the term- Data Flows Data Flows:...

Explain the term- Data Flows Data Flows: A data flow connects output of an object or process to input of another process or object. It represents an in-between data value wit

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