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What is Database Fragmentation? Advantages and Disadvantages of Fragmentation


What is Database Fragmentation?
The database table is divided into smaller subsets of different table. These divided subsets are called fragment of table.



The table can be divided into three type of fragment

  1. Vertical Fragmentation
  2. Horizontal Fragmentation
  3. Mixed Fragmentation


Advantages of Fragmentation


Usage
In general, applications work with views rather than entire relations.

Therefore, for data distribution, it seems appropriate to work with subsets of relation as the unit of distribution.

Efficiency
Data is stored close to where it is most frequently used.

In addition, data that is not needed by' local applications is not stored.

Parallelism

With fragments as the unit of distribution, a transaction can be divided into several sub queries that operate on fragments.

This should increase the degree of concurrency, or parallelism, in the system, thereby allowing transactions that can do so safely to execute in parallel.

Disadvantages of Fragmentation

Performance

The performance of global application that requires data from several fragments located at different sites may be slower. 

Integrity

Integrity control may be more difficult if data and functional dependencies are fragmented and located at different sites.

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