Random (Hashed) File and Index File

Introduction
There are distinct non-sequential file structure models in the computer system, generally, the file structure can be subdivided into two major types which are the random (hashed) file and the index file. This will compare the both types of file structure models and its advantages and disadvantages.

The random (hashed) file
It is quite useful of this type structuring system while the files are non-sequential that can be depicted as data storage spaces and which are subdivided into the compartments that is named buckets. Data then issued to the buckets relying on the main value computed by hash effect. It is quite important at this pint well computed hash effect as it would allow crowding. The hashed files map datas to HDD places not by applying an index, yet via an algorithm alteration that is advantageous in decreasing the dimensional consumptions made by the index as well as and time wasting that are caused by extra access and binary search. The OS holds a key to save, recall and map the datas. Thus it is optimization completed on the process to eliminate space overheads by applying means such as partitioning the key by a initial digital to obtain the file 's unique addresses.

The index file
It is a good design astuteness and resourcefulness of sequential files for saving data. However, the issue occurs when restore the data and quickly. General settling of the issue is used an index file. As J. Glenn Brookshear states at his book that "An index for a file contains a list of the keys stored in the file along with entries indicating where the record containing each key is stored”. Therefore for the purpose of searching a particular data have to find the key in the index file and then restore the block of intelligence. Index file is often saved on a distinct storage place. For faster the processing, index file is delivered to primary memory. Commonly, there are two sections of Indexed files, the first one that data is located on the HDD and the sorted-list lets the second element that possess two areas to keep the pointer and key, this can be decrease the process time. Indexed files do net demand the data to be in any particular sequence that the file 's index is similar the book 's index which for looking for details during the book.

Advantages and Disadvantages of the both types
The both file system types have their advantages and disadvantages that hashed files are better for the files where order is unimportant, it must access the none or entire file, such as the image, binary and

zip files. These files are ineffective in case the files are not accessed as an entire; so possessing the preceding of index is not too much significance. The format of hashed file is beneficial in verifying the file contents as well as it is the most generally used format. In the other hand, the advantages of index files is that when the records to be saved is structured as well as require to search the record from any file place, then the index files are the best to apply. The best instance of them index file is the file saving records of employees ' profile. the other instance that completely illustrates them is concerned to the realistic file system where hierarchic folder architecture is the files ' index. Actually, the entire file system is similar an index file.

Conclusion We can summarize the both types of files system as the following: 1. Index files have larger size 2. If request more security, then Hashed system will be more suitable. 3. If need to fast access the file, then should choose Index files. 4. Using Hashed files are better for discreet data. 5. Using hashed files can better administer HDD space. 6. Using Index file is better for structured data 7. Image, video and Sound formats are the good example of hashed files. 8. Files systems, E-mails and OS are the good example of index files. References
Computer Science: An Overview; J. Glenn Brookshear Tutorial: HBase -- Theory and Practice of a Distributed Data Store; Pietro Michiardi available on: (http://www.eurecom.fr/~michiard/teaching/slides/clouds/tutorial-hbase.pdf )

References: Computer Science: An Overview; J. Glenn Brookshear Tutorial: HBase -- Theory and Practice of a Distributed Data Store; Pietro Michiardi available on: (http://www.eurecom.fr/~michiard/teaching/slides/clouds/tutorial-hbase.pdf )