File organisation:
File organisation refers to the logical relationships among various records that constitute the file, particularly with respect to the means of identification and access to any specific record. In short, storing the files in a certain order is called file organisation.
Types of file organisation:
1. Sequential file organisation: Sequential file organisation is the easiest method. In this method files are stored one after the other in a sequential manner. This method is also called a Pile or sorted file.
This method is fast & efficient for huge amounts of data. Sorted files are inefficient as it takes time & space for sorting records.
2. Serial file organisation: Serial file organisation is also called a heap file. In this method, records are inserted at the end of the file into the data blocks. There is no requirement of sorting data.
When a huge amount of data is to be inserted at a time in an organisation, that time this method is suitable. Accessing of data is slower as compared to sorted file method
3. Index Sequential Access Method (ISAM): ISAM method is advanced sequential file organisation. In this method, index value is generated and mapped with every record. Using that index, accessing of record is done
4. Random access / Direct access file organisation: In this file organisation records are stored randomly but accessed directly. To access a file stored randomly, a record key is used to determine where a record is stored on the storage media. Magnetic and optical disks allow data to be stored and accessed randomly.
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