Distributed Database Systems

A distributed database system is a database in which data is not stored on a single centralized machine but is instead spread across multiple interconnected computers, or nodes, often in different physical locations. While the data is physically partitioned and/or replicated across the network, the system presents a unified, single-database view to the user, masking the underlying complexity. This architecture is designed to achieve significant benefits, including enhanced scalability to handle large volumes of data and traffic, high availability and fault tolerance through data redundancy, and improved performance by processing queries in parallel and placing data closer to users, though it introduces challenges in maintaining data consistency across all nodes.

1. Fundamentals of Distributed Systems
   1. Definition and Characteristics of Distributed Database Systems
      1. Definition of a Distributed Database System
      2. Key Features of DDBMS
      3. Components of a DDBMS
         1. Database Management Software
         2. Communication Network
         3. Transaction Manager
         4. Data Dictionary
   2. Comparison with Other Database Systems
      1. Centralized Database Systems
         1. Architecture
         2. Advantages and Disadvantages
      2. Parallel Database Systems
         1. Architecture
         2. Use Cases
         3. Differences from DDBMS
      3. Federated Database Systems
         1. Architecture
         2. Autonomy and Heterogeneity
         3. Comparison with DDBMS
   3. Motivations for Distribution
      1. Scalability Requirements
         1. Horizontal Scaling
         2. Vertical Scaling
      2. High Availability and Reliability
         1. Fault Tolerance
         2. Redundancy
      3. Performance Improvement
         1. Load Balancing
         2. Locality of Reference
      4. Organizational Autonomy
         1. Decentralized Control
         2. Data Ownership
      5. Geographic Distribution
      6. Cost Considerations
   4. Inherent Challenges in Distributed Systems
      1. Increased Complexity
         1. System Design Complexity
         2. Maintenance Challenges
      2. Concurrency Control
         1. Distributed Transactions
         2. Synchronization Issues
      3. Data Consistency
         1. Consistency Models
         2. Data Integrity
      4. Security Concerns
         1. Distributed Threat Surface
         2. Data Privacy
      5. Failure Management
         1. Site Failures
         2. Network Failures
         3. Recovery Mechanisms
      6. Communication Overhead
      7. Heterogeneity Issues
   5. Twelve Rules for a DDBMS
      1. Rule 0: Distributed Database System Rule
      2. Rule 1: Local Autonomy
      3. Rule 2: No Reliance on a Central Site
      4. Rule 3: Continuous Operation
      5. Rule 4: Location Independence
      6. Rule 5: Fragmentation Independence
      7. Rule 6: Replication Independence
      8. Rule 7: Distributed Query Processing
      9. Rule 8: Distributed Transaction Processing
      10. Rule 9: Hardware Independence
      11. Rule 10: Operating System Independence
      12. Rule 11: Network Independence