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Questions and Answers
What is the rule of Completeness in fragmentation?
Which operation is used for reconstruction in horizontal fragmentation?
What operation can reconstruct the Staff relation from the provided fragments?
What is the purpose of Disjointness in fragmentation?
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Why is it important for the fragments to be disjoint in a distributed database system?
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Why does Integrity control become more difficult with fragmented data?
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What is the primary key used in the provided text for the Staff relation?
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Why is it mentioned that the Branch relation is not updated very frequently in the given text?
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What is the primary purpose of Fragmentation in database design?
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In the context of fragmentation, what is one reason for replicating the Branch relation at each site instead of horizontally fragmenting it?
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What type of operation ensures that there can be no staff member who works in more than one branch based on the provided information?
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In fragmentation, what does Reconstruction aim to achieve?
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What is the main purpose of fragmentation in database design?
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What is a key aspect of the completeness property of fragmentation?
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What is the reconstruction property of fragmentation in database design?
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In distributed databases, what does disjointness refer to?
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How does fragmentation contribute to data consistency in distributed databases?
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Which relational operation is mentioned in the text as essential for reconstructing the original relation from fragments?
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Study Notes
Completeness in Fragmentation
- Completeness ensures that the original relation can be reconstructed exactly from its fragments.
- The rule requires that the union of all fragments must equal the original dataset.
Reconstruction Operation
- Relational operations such as JOIN are used for reconstruction in horizontal fragmentation.
- JOIN combines fragments to recreate the full dataset while maintaining data relationships.
Reconstruction of Staff Relation
- The Staff relation can be reconstructed from fragments using JOIN operations on the relevant data subsets.
Purpose of Disjointness in Fragmentation
- Disjointness ensures that no data tuples are shared between fragments, preventing duplication.
- It maintains data integrity by making sure each tuple belongs to one unique fragment.
Importance of Disjoint Fragments
- Disjoint fragments simplify data management by reducing redundancy.
- They enhance performance and efficiency in data retrieval in distributed systems.
Integrity Control Challenges
- Integrity control becomes difficult due to the potential for inconsistencies across multiple fragments.
- Maintaining data validity and constraints requires additional monitoring and systems.
Primary Key for Staff Relation
- The primary key for the Staff relation is typically a unique identifier, ensuring that each staff member is distinct.
Branch Relation Update Frequency
- The Branch relation is not updated frequently, indicating stable data with fewer changes, which aids performance.
Purpose of Fragmentation
- Fragmentation optimizes performance and storage by partitioning large databases into manageable pieces.
- It enhances query efficiency by allowing localized access to data.
Replication of Branch Relation
- Replicating the Branch relation at each site can provide faster access and improved availability compared to horizontal fragmentation.
Staff Member Assignment Operation
- An operation such as RESTRICT ensures that no staff member works in more than one branch, enforcing business rules.
Aim of Reconstruction
- Reconstruction aims to achieve a complete and accurate dataset from assembled fragments, restoring original relationships.
Main Purpose of Database Fragmentation
- The primary goal of fragmentation in database design is to improve performance and manageability of data across distributed systems.
Completeness Property Aspect
- A key aspect of completeness is that every piece of data must be represented in at least one of the fragments.
Reconstruction Property
- The reconstruction property guarantees that fragments can be combined through operations to perfectly recreate the original dataset.
Disjointness in Distributed Databases
- In distributed databases, disjointness refers to fragments being non-overlapping, ensuring clear data ownership and minimizing conflicts.
Fragmentation and Data Consistency
- Fragmentation contributes to data consistency by clearly defining data ownership and scope, allowing precise updates and retrievals.
Essential Relational Operation
- JOIN is mentioned as the essential relational operation for reconstructing the original relation from its fragments.
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Description
Test your knowledge on database fragmentation with a quiz that involves identifying and analyzing data fragments from multiple tables. Understand how to combine fragmented data to retrieve complete information on staff members.
