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
- Vertical Fragmentation
- Horizontal Fragmentation
- 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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