File Organization Method

File organization means the way of storing data in secondary device. In secondary device the data that is stored is first converted into binary format because physical device understand only 1, 0 characters. The way to access and find stored data is called access method. Retrieval method depends on the way the records are stored in the memory (main memory, secondary memory).

Advantages and disadvantages of file organization method

                          A database uses three basic method of storing files in a storage media. These methods are as follows:

1.   Sequential file organization method

Advantages of a sequential file organization method:-

1.   In sequential file organization records are stored in sequence.

2.   The records are stored on storage device (magnetic tape etc) in increasing ( 1, 2, 3,4 …….. 10) or decreasing ( 10, 9, 8, 7 …… 1)

3.   In this method records are stored one after another and in the same way retrieving the records in the same order in which the records are stored.

4.   Sequential file organization method is very simple and easy to manage.

5.   Sequential organization is used for backup.

6.   This method of organization is less expansive (magnetic tape).

Disadvantages of a sequential file organization method:-

1.   In sequential file organization it is not possible to access records randomly it means that if we want to retrieve record 4 then it move from record 1 to record 4it is not possible to pick record 4 directly.

2.   In sequential organization we do not insert a record in the middle of row. The new record always insert in the end of the row.

3.   Sequential organization is very slow and does not provide immediate updates.

2.   Indexed sequential file organization method

Advantages of an indexed sequential file organization method:-

1.   Indexes are maintains in the file. Index is a key value that refers to a place where a record is stored.

2.   This method can use a both technique sequential file organization and direct file organization method.

3.   Index sequential file organization is efficient and provides an immediate updates.

4.    In this method record is inserted or deleted in any place and index file is updated.

Disadvantages of an indexed sequential file organization method:-

1.   This method is slow and time consuming

2.   It requires a large space in a storage media because to maintain an index file in the storage media.

3.   Direct file organization method

     Advantages of a direct file organization method:-

1.   In direct file organization record are stored by using a key value. Direct file organization is faster to find a specific record.

2.   Direct file organization use a hash scheme.

 Disadvantages of a direct file organization method:-

1.   The same address is calculated to store two or more records.

2.   Accidental Deletion or updation of data