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File Organization in DBMS – Set 1

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A database consists of a huge amount of data. The data is grouped within a table in RDBMS, and each table has related records. A user can see that the data is stored in the form of tables, but in actuality, this huge amount of data is stored in physical memory in the form of files. 

What is a File?

A file is named a collection of related information that is recorded on secondary storage such as magnetic disks, magnetic tapes, and optical disks

What is File Organization?

File Organization 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 simple terms, Storing the files in a certain order is called File Organization. File Structure refers to the format of the label and data blocks and of any logical control record. 

The Objective of File Organization

  • It helps in the faster selection of records i.e. it makes the process faster.
  • Different Operations like inserting, deleting, and updating different records are faster and easier.
  • It prevents us from inserting duplicate records via various operations.
  • It helps in storing the records or the data very efficiently at a minimal cost

Types of File Organizations

Various methods have been introduced to Organize files. These particular methods have advantages and disadvantages on the basis of access or selection. Thus it is all upon the programmer to decide the best-suited file Organization method according to his requirements. 

Some types of File Organizations are: 

  • Sequential File Organization
  • Heap File Organization 
  • Hash File Organization 
  • B+ Tree File Organization 
  • Clustered File Organization
  • ISAM (Indexed Sequential Access Method)
     

We will be discussing each of the file Organizations in further sets of this article along with the differences and advantages/ disadvantages of each file Organization method. 

Sequential File Organization

The easiest method for file Organization is the Sequential method. In this method, the file is stored one after another in a sequential manner. There are two ways to implement this method:

1. Pile File Method

This method is quite simple, in which we store the records in a sequence i.e. one after the other in the order in which they are inserted into the tables. 

Pile File Method

Pile File Method

Insertion of the new record: Let the R1, R3, and so on up to R5 and R4 be four records in the sequence. Here, records are nothing but a row in any table. Suppose a new record R2 has to be inserted in the sequence, then it is simply placed at the end of the file. 

New Record Insertion

New Record Insertion

2. Sorted File Method

In this method, As the name itself suggests whenever a new record has to be inserted, it is always inserted in a sorted (ascending or descending) manner. The sorting of records may be based on any primary key or any other key. 

Sorted File Method

Sorted File Method

Insertion of the new record: Let us assume that there is a preexisting sorted sequence of four records R1, R3, and so on up to R7 and R8. Suppose a new record R2 has to be inserted in the sequence, then it will be inserted at the end of the file and then it will sort the sequence. 

new Record Insertion

new Record Insertion

Advantages of  Sequential File Organization

  • Fast and efficient method for huge amounts of data.
  • Simple design.
  • Files can be easily stored in magnetic tapes i.e. cheaper storage mechanism.

Disadvantages of  Sequential File Organization

  • Time wastage as we cannot jump on a particular record that is required, but we have to move in a sequential manner which takes our time.
  • The sorted file method is inefficient as it takes time and space for sorting records. 

Heap File Organization

Heap File Organization works with data blocks. In this method, records are inserted at the end of the file, into the data blocks. No Sorting or Ordering is required in this method. If a data block is full, the new record is stored in some other block, Here the other data block need not be the very next data block, but it can be any block in the memory. It is the responsibility of DBMS to store and manage the new records. 

Heap File Organization

Heap File Organization

Insertion of the new record: Suppose we have four records in the heap R1, R5, R6, R4, and R3, and suppose a new record R2 has to be inserted in the heap then, since the last data block i.e data block 3 is full it will be inserted in any of the data blocks selected by the DBMS, let’s say data block 1.

New Record Insertion

New Record Insertion

If we want to search, delete or update data in the heap file Organization we will traverse the data from the beginning of the file till we get the requested record. Thus if the database is very huge, searching, deleting, or updating the record will take a lot of time.

Advantages of Heap File Organization

  • Fetching and retrieving records is faster than sequential records but only in the case of small databases.
  • When there is a huge number of data that needs to be loaded into the database at a time, then this method of file Organization is best suited.

Disadvantages of Heap File Organization

  • The problem of unused memory blocks.
  • Inefficient for larger databases.

Conclusion

In Conclusion, it is critical to choose the appropriate file organization in a database management system (DBMS). While random structure offers flexibility but may lead to fragmentation, sequential arrangement is better for ordered access. Indexing finds a balance, clustering improves efficiency for particular queries, and hashed structures maximize speedy access. Sustained efficiency requires routine maintenance. The selection should be based on the requirements of the particular application; for best DBMS performance, a careful combination of strategies may be required.

FAQs on File Organization

Q.1: What is File Organization?

Answer:

File Organization is basically a relationship among the different records that makes the file where the identification and access to any record become easier.

Q.2: What are the four methods of file organization?

Answer:

The methods of file organization are 

  • Sequential
  • Random
  • Serial
  • Indexed Sequential

Q.3: What is the difference between Sequential File Organization and Heap File Organization?

Answer:

The simple difference between the Sequential File Organization and Heap File Organization is that Sequential File Organization places the data in the proper sequence whereas Heap File Organization places data in arbitrary order. 

For more, refer to DBMS File Organization – Set 2 | Hashing in DBMS.



Last Updated : 16 Nov, 2023
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