Define distributed database system. Explain the promises of DDB. List the transparencies provided by DDBS.

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Distributed Database System (DDBS)

A Distributed Database System (DDBS) is a database system where the data is stored across multiple physical locations (sites), but it works as a single unified system. These sites are connected via a network, and users interact with the system as though it’s one database, even though the data is distributed.

Promises of Distributed Database System (DDBS)

A Distributed Database System comes with several promises that make it very useful for businesses and organizations:

  1. Data Distribution:
    • The data is spread across multiple locations (sites). These sites can be in different physical locations, such as different cities or countries, but the system makes it look like one database.
  2. Scalability:
    • As the amount of data grows, the system can easily grow by adding more sites or servers. This helps the database handle more users and larger amounts of data.
  3. Availability and Fault Tolerance:
    • Even if one site or server fails, the system can still work, because the data is often replicated (copied) across multiple sites. This ensures that the data is always available.
  4. Better Performance:
    • Queries (requests for data) can be handled faster because the system can distribute the workload across multiple sites. This reduces the time it takes to get results for large queries.
  5. Reliability:
    • Distributed databases ensure that data is safe and won’t be lost, even if one part of the system fails. Replication and backup mechanisms keep the data safe.
  6. Location Transparency:
    • Users don’t need to know where the data is stored. The system makes it appear as if all the data is in one place, even though it’s spread across different locations.
  7. Load Balancing:
    • The system automatically balances the workload across different sites, making sure that no single site becomes overloaded with too many requests.
  8. Concurrent Access:
    • Multiple users can access and modify the data at the same time without causing problems, thanks to the system’s ability to manage concurrent transactions effectively.

Transparencies in Distributed Database Systems (DDBS)

A transparency in a distributed database system means that the user doesn’t need to worry about the complexity of how the data is stored or accessed across different sites. The system hides these complexities and makes it easy for users to interact with the data. Here are the key types of transparencies in a DDBS:

  1. Location Transparency:
    • Users don’t need to know where the data is stored. They can access the data without being aware of its physical location in the network.
  2. Fragmentation Transparency:
    • Data can be divided into parts, called fragments. The system makes sure the user doesn’t need to know how the data is divided or how the fragments are stored at different locations.
  3. Replication Transparency:
    • Data can be copied (replicated) to multiple sites. The system handles replication, so users don’t need to know if they are accessing the original data or a replica.
  4. Concurrency Transparency:
    • Multiple users can work with the data at the same time without interfering with each other. The system makes sure that concurrent transactions are handled correctly.
  5. Transaction Transparency:
    • The system handles transactions in a way that users don’t need to worry about how data is updated or rolled back, even if the transaction involves multiple sites.
  6. Access Transparency:
    • Users can access data in the same way, whether it’s stored locally or at a remote site. The system hides the difference in how the data is accessed.
  7. Network Transparency:
    • The system hides the details of the network from users. Users don’t need to worry about how data is transferred over the network between different sites.
  8. Performance Transparency:
    • The system automatically adjusts its performance based on the workload. It balances the load and ensures that users experience consistent performance, even as data grows or more users join.

Hence, a Distributed Database System (DDBS) is a database system where data is stored in multiple locations, but it appears as one system. It offers benefits like better performance, scalability, and fault tolerance. The system hides the complexity of data distribution through various transparencies, making it easy for users to interact with data without worrying about where it’s stored or how it’s managed.

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