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Questions and Answers
What is a characteristic of a fully replicated distributed database?
What is a characteristic of a fully replicated distributed database?
Which type of distributed database management system (DDBMS) operates with uniform software across all nodes?
Which type of distributed database management system (DDBMS) operates with uniform software across all nodes?
What type of data allocation involves storing each fragment at only one site?
What type of data allocation involves storing each fragment at only one site?
Which of the following issues may arise in federated database management systems?
Which of the following issues may arise in federated database management systems?
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In a client-server database architecture, what do clients run?
In a client-server database architecture, what do clients run?
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What is one of the primary components of a distributed computing system?
What is one of the primary components of a distributed computing system?
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Which type of transparency allows users to access data without needing to know its physical location?
Which type of transparency allows users to access data without needing to know its physical location?
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What defines the reliability of a distributed system?
What defines the reliability of a distributed system?
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Which characteristic describes the system’s ability to continue functioning during network partitioning?
Which characteristic describes the system’s ability to continue functioning during network partitioning?
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What aspect of a distributed database ensures that certain types of faults do not affect the overall system's availability?
What aspect of a distributed database ensures that certain types of faults do not affect the overall system's availability?
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Which type of autonomy refers to the independence of data models and transaction management techniques?
Which type of autonomy refers to the independence of data models and transaction management techniques?
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Which of the following is NOT an advantage of distributed databases?
Which of the following is NOT an advantage of distributed databases?
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What type of scalability involves expanding the number of nodes in a distributed database?
What type of scalability involves expanding the number of nodes in a distributed database?
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What is horizontal fragmentation also known as?
What is horizontal fragmentation also known as?
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What operation is used to reconstruct a relation from complete vertical fragmentation?
What operation is used to reconstruct a relation from complete vertical fragmentation?
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Which type of fragmentation keeps only certain attributes of a relation?
Which type of fragmentation keeps only certain attributes of a relation?
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What is the primary purpose of replication in distributed systems?
What is the primary purpose of replication in distributed systems?
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How are mixed fragmentations defined?
How are mixed fragmentations defined?
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What does complete horizontal fragmentation require to reconstruct the original relation?
What does complete horizontal fragmentation require to reconstruct the original relation?
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Which of the following describes a drawback of non-distributed systems compared to distributed systems?
Which of the following describes a drawback of non-distributed systems compared to distributed systems?
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What does replication strategy involve in distributed systems?
What does replication strategy involve in distributed systems?
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Study Notes
Distributed Databases
- Distributed computing systems consist of interconnected nodes
- These nodes work together to perform tasks efficiently
- Distributed databases connect database nodes over a computer network
- The connected databases form a logical interrelation
- Databases might not have homogeneity among the nodes
- A distributed database management system (DDBMS) handles the distributed database
Introduction
- A distributed database is a collection of multiple databases spread across different physical locations
- Accessing data in a centralized database takes more time than in a distributed database for multiple users
- Modification, management, and backup are more challenging in distributed databases compared to centralized ones
- A uniform view is harder to provide to users across locations
- Data consistency may be affected in distributed databases
- User access may be reduced if one database fails, but distributed databases have access to multiple others
- Distributed databases are more costly compared to centralized ones
Transparency
- Transparency hides implementation details from users, giving a seamless experience
- Types of transparency include data organization, location, naming, replication, fragmentation (horizontal and vertical), design, and execution transparency
Availability and Reliability
- Availability is the probability of a system being continuously operational during a time interval
- Reliability shows the probability that a system operates without issues at any given time
Scalability and Partition Tolerance
- Horizontal scalability increases the number of nodes
- Vertical scalability improves the capacity of individual nodes
- Partition tolerance ensures system operation even during network partition
Autonomy
- Autonomy describes the extent where nodes can operate independently
- Types of autonomy include design (data model and transaction), communication (sharing information), and execution (user actions)
Advantages of Distributed Databases
- Application development can occur in different geographic locations
- Failures in one location don't affect overall availability
- Data localization reduces network traffic, improving performance
- Expansion is easier, whether by adding new nodes or improving individual node capacity
Data Fragmentation, Replication, and Allocation Techniques
- Fragments are logical units of a database distributed across nodes
- Horizontal fragmentation divides a relation into parts based on conditions or methods
- Vertical fragmentation segments a relation by columns, keeping necessary attributes
- Replication and allocation strategies manage fragment and replica storage across nodes for performance and availability
- Fully replicated databases copy the entire database on all sites
- Non-redundant allocation stores each fragment in a specific location
- Partial replication duplicates some but not all fragments
Mixed Fragmentation
- Combining horizontal and vertical fragmentation techniques
Types of Distributed Database Systems
- Homogeneous DDBMS: Uses the same software on all nodes
- Heterogeneous DDBMS: Uses different software and configurations on different nodes
- Federated databases (FDBS): Feature a shared global schema, with issues involving differences in data models, constraints, query languages, and semantic heterogeneity
Client-Server Database Architecture
- Client-server architecture includes client software, servers providing database functions, and a reliable communication infrastructure
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Description
Explore the fundamentals of distributed databases, which are collections of databases spread across various physical locations. Understand the advantages they offer over centralized systems and the challenges in management, data consistency, and user access. This quiz will help you grasp the key concepts in distributed database management systems (DDBMS).
