Database/SQL
In a sharded database architecture deployed on cloud infrastructure, which of the following represents the most critical challenge that must be addressed?
A
Shard key selection and distribution skew
B
Implementing full-text search across shards
C
Eliminating all network latency between shards
D
Converting all queries to read-only operations
Correct Answer:
A. Shard key selection and distribution skew
Shard key selection determines data distribution and performance. Poor shard key choices lead to hotspots, uneven load distribution, and performance degradation across the sharded cluster.
In AI/ML, what is the role of activation functions in neural networks?
A
Encrypt network weights
B
Introduce non-linearity enabling networks to learn complex patterns
C
Increase training speed
D
Reduce dataset size
Correct Answer:
B. Introduce non-linearity enabling networks to learn complex patterns
Activation functions (ReLU, sigmoid, tanh) add non-linearity, allowing neural networks to approximate non-linear relationships.
What is the primary challenge of implementing ACID properties in distributed databases?
A
Requires minimal network latency
B
Network partitions, latency, and node failures make maintaining consistency difficult while ensuring availability
C
Distributed systems automatically ensure ACID
D
Only centralized databases can support ACID
Correct Answer:
B. Network partitions, latency, and node failures make maintaining consistency difficult while ensuring availability
The CAP theorem shows it's impossible to guarantee all three: Consistency, Availability, and Partition tolerance simultaneously.
In distributed systems, what is a consensus algorithm primarily used for?
A
Encrypting data
B
Ensuring all nodes agree on a single value despite failures
C
Compressing database files
D
Load balancing across servers
Correct Answer:
B. Ensuring all nodes agree on a single value despite failures
Consensus algorithms (like Raft, Paxos) enable distributed systems to reliably agree on state even with node failures.
In database normalization, what does the Boyce-Codd Normal Form (BCNF) address that 3NF might miss?
A
Elimination of multivalued dependencies
B
Removal of anomalies from composite candidate keys
C
Prevention of circular foreign keys
D
Ensuring data type consistency
Correct Answer:
B. Removal of anomalies from composite candidate keys
BCNF handles edge cases in 3NF where anomalies can occur with composite candidate keys where determinants are not candidate keys themselves.
In a B-tree of order m, what is the maximum number of keys that a non-root node can contain?
A B-tree of order m can have at most 2m-1 keys in any node and minimum m-1 keys in non-root nodes.
What is the primary advantage of using GraphQL over traditional REST APIs in modern application architecture?
A
GraphQL always provides better performance
B
GraphQL allows clients to request only required data fields, reducing over-fetching
C
GraphQL eliminates the need for databases
D
REST APIs are completely replaced by GraphQL
Correct Answer:
B. GraphQL allows clients to request only required data fields, reducing over-fetching
GraphQL's query language enables clients to specify exact data requirements, eliminating over-fetching and under-fetching issues common in REST.
In cybersecurity, what is SQL injection and why is it a critical vulnerability in 2024?
A
Injecting SQL commands to execute unauthorized database operations
B
A performance optimization technique
C
A method to improve database security
D
An outdated vulnerability no longer relevant
Correct Answer:
A. Injecting SQL commands to execute unauthorized database operations
SQL injection allows attackers to insert malicious SQL code through application inputs, remaining a critical OWASP Top 10 vulnerability despite awareness.
Which of the following best describes a distributed transaction and its challenges in microservices architecture?
A
Transactions that execute only on primary databases
B
Transactions spanning multiple services requiring coordination and handling failures
C
Transactions that cannot be executed in microservices
D
Local transactions that never require coordination
Correct Answer:
B. Transactions spanning multiple services requiring coordination and handling failures
Distributed transactions in microservices require mechanisms like Saga pattern or Two-Phase Commit to maintain consistency across services.
In database replication, what is the primary difference between synchronous and asynchronous replication?
A
Synchronous is always faster
B
Asynchronous waits for replica confirmation; Synchronous does not
C
Synchronous waits for replica confirmation; Asynchronous does not
D
Both have identical performance characteristics
Correct Answer:
C. Synchronous waits for replica confirmation; Asynchronous does not
Synchronous replication waits for replicas to acknowledge writes (safer but slower), while asynchronous replication doesn't wait (faster but less safe).
