Sakar Pradhananga

Explain the challenges of managing views in distributed databases. How do updates through viewsdiffer in centralized vs. distributed systems?

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1. Data Fragmentation and DistributionChallenge: Views often need to aggregate or join data from multiple fragments distributed acrossdifferent nodes.Impact: This increases query complexity and communication overhead, as data must be fetched frommultiple locations. 2. Consistency MaintenanceChallenge: Ensuring that views reflect the most up-to-date data from underlying base tables, especiallywhen data is updated at different nodes.Impact: … Read more

Discuss the significance of autonomy, distribution, and heterogeneity in DDB architectural models.How do these factors influence system design?

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1. Autonomy in DDB Systems: Autonomy refers to the degree of independence each database site has interms of control over its own data, transaction management, and query execution. Types of Autonomy:i. Design Autonomy: Each site can define its schema and constraints independently.ii. Execution Autonomy: Each site can decide how to execute queries and transactions.iii. Communication … Read more

Compare horizontal and vertical fragmentation in distributed databases. Provide examples toillustrate how each technique optimizes query performance.

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Fragmentation in Distributed Databases Fragmentation is the process of breaking a large database into smaller parts, called fragments, which are stored across different locations. These fragments ensure that data can be efficiently managed and accessed while maintaining the ability to rebuild the original database without losing any information. For example, if a table T is … Read more

Explain the basic concepts of distributed databases and why they are necessary in modern computingenvironments.

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A distributed database is a database that is not stored at a single location but is distributed across multiple physical sites or servers. These sites may be located in different geographical locations, and the data is partitioned or replicated across these locations. Each site or node in a distributed database system can independently process transactions, … Read more

Define beneficial semi join. How do you choose best join order in System R algorithm? Explain with example. Descibe hill climbing algorithm to find the initial feasible solution.

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A beneficial semi join is a type of join optimization technique used in distributed databases, especially when performing joins across sites in a distributed system. The goal is to reduce the amount of data transferred between sites by using a “semi join” approach. A semi join involves sending only the keys (or attributes) from one … Read more

Explain query decomposition layer in distributed query processing with examples.

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Query decomposition is a critical step in distributed query processing where a complex SQL query is broken down into simpler, smaller sub-queries that can be executed across different sites or nodes in a distributed database system. The goal of this process is to ensure that each sub-query can be processed locally, reducing the overhead of … Read more

Explain distributed integrity constraints. “Enforcing distributed integrity assertions is more complex than needed in centralized DBMS, even with global transaction management support” elaborate this sentence with proper constraints and examples.

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Distributed Integrity Constraints are rules that ensure data consistency, accuracy, and reliability across multiple sites in a Distributed Database Management System (DDBMS). These constraints help maintain data integrity even when data is stored at different locations and accessed by multiple users simultaneously. The types of distributed integrity constraints are as follows: i. Primary Key Constraint: … Read more

Describe COM_MIN approach in horizontal fragmentation, How do you obtain clustered affinity matrix in vertical fragmentation? Explain with suitable example.

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COM_MIN Approach in Horizontal Fragmentation The COM_MIN (Complete and Minimal) approach is used in horizontal fragmentation to divide a database table into smaller, meaningful parts based on query conditions. The goal is to ensure that each fragment contains only the necessary data, making queries faster and reducing communication between database servers. How it Works: i. … Read more

Discuss the three architectures of Distributed DBMS.

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A Distributed Database Management System (DDBMS) is a software system that manages a database distributed across multiple locations, interconnected by a network, yet presents it as a unified database to users. This distribution allows data to be stored closer to where it’s needed, enhancing accessibility and performance. The key characteristics of a DDBMS are: i. … Read more

What is Distributed Database? How does it differ from centralized Database? Explain Detail.

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A Distributed Database is a collection of data that is spread across multiple physical locations, interconnected via a network. Each site, or node, operates independently, processing local transactions while contributing to the overall database system. This architecture enhances the database’s availability and resilience to failures. Distributed database is different from centralized database in the following … Read more