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Data Management Issue in Mobile Database
Data management that allows to access data from devices is the main problem. The mobile database allows applications to access data from devices even when on the move. It is a database that connects devices over a wireless network. Here, the client and server have a wireless connection. The wired connections have the entire database distributed with full or partial replication. Fixed hosts are there to perform data management with the help of database servers. Base stations are present at fixed locations to pass communication with the mobile units to and from the fixed hosts.
Issues that arise in data management of mobile databases are:
Mobile Database Design
On account of the continuous closure and for dealing with the queries, the worldwide name goal issue is compounded.
Security
Data security is an important aspect for a user. The data which are there are more safe compared to mobile data. Data are becoming unpredictable and actions must be taken for its loss. The main thing is the proper authorization access of any data with specific strategies.
Data Distribution and Replication
The distribution of data among the mobile units and base stations is uneven. The issue related to cache management is combined with consistency constraints. Cache provides data to mobile units that are most updated and frequently asked and doing their transaction. The most efficient data with higher security is accessible.
Replication Issues
Due to the increase in the number of replicas i. e. increase in a copy of the database, there is an increase in the cost of updation and signaling.
Division of labor
Some scenarios are there in which the client must function independently of the server. Changes occur in the division of labor in query processing because of specific properties of the mobile environment.
Transaction Models
Transaction can be defined as a group of tasks. The issues of accuracy of transactions and adaptation to non−critical failure are exasperated. The transaction must have Atomicity, Consistency, Isolation, and Durability known as ACID properties. ACID property is hard to apply when mobile computers get disconnected. Because of disconnection in mobile units, it is expected that a mobile transaction will sustain long. Mobile transaction execution depends upon the movement of multiple data set through several base stations.
Recovery and Fault Tolerance
Fault tolerance means the system will be performing tasks correctly even if there is a presence of an internal fault. Faults are of two types: Transient and Permanent. Transient fault will disappear without any interference whereas Permanent fault will be present unless removed by someone. If a desired shutdown happens in the mobile unit then it is not treated as a failure. Transaction failure happens during handoff and then network partitioning takes place. The characterization of mobile computing is done by Limiting resource availability, Frequent disconnection, High mobility, and Low bandwidth
Location−Based Service
Tracking location is a tough task and is present to enable a location−based service. Eviction techniques are important in this case. The main problem is the updation of location−dependent queries and then using spatial queries to refresh. Some other issues are User Privacy, Diverse mobile mapping standards, Market capability, and Interoperability
Query Processing
Query processing becomes complicated because of mobility and data change on the mobile unit. Mobility has a great impact on query processing. The cost that affects most in centralized environments is input/output.
Conclusion
Above discussed things are how the data is managed in a mobile database and the issues that are being faced i. e. database design, security of data, data distribution and replication, division of labor, transaction models, Recovery and fault tolerance, location−based services, and query processing.
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