241. What is database observability?
- a) Monitoring + logging + tracing
- b) Query performance tuning
- c) Schema visualization
- d) Data lineage tracking
Answer: A - Holistic visibility into database health and performance (OpenTelemetry integration).
242. Which SQL feature enforces data contracts?
- a) CHECK constraints
- b) Schema validation
- c) Foreign keys
- d) All of the above
Answer: D - Guarantees data structure/quality between systems.
243. What is a unified query engine?
- a) Processes multiple data formats with one syntax
- b) Combines SQL and NoSQL
- c) Federates queries across clouds
- d) All of the above
Answer: A - Examples: Trino, Apache Drill, BigQuery Omni.
244. Which database accelerates neural networks?
- a) PostgreSQL with pgvector
- b) SQL Server with ML Services
- c) Oracle Database with Graph
- d) All of the above
Answer: D - In-database deep learning optimizations.
245. What is homomorphic encryption in databases?
- a) Computations on encrypted data
- b) Quantum-safe algorithms
- c) Multi-party encryption
- d) Blockchain-based security
Answer: A - Emerging research area (Microsoft SEAL, IBM HE).
246. Which statement creates an observable metric?
- a) CREATE METRIC
- b) DEFINE TELEMETRY
- c) ENABLE MONITORING
- d) Implementation-specific
Answer: D - Snowflake/SQL Server/Oracle use different syntax.
247. What is the purpose of the SQL VALIDATE_CONTRACT() function?
- a) Verifies schema/data compliance
- b) Tests encryption
- c) Checks permissions
- d) Audits queries
Answer: A - Ensures data meets predefined specifications.
248. Which database provides native JSON schema validation?
- a) MongoDB
- b) PostgreSQL
- c) SQL Server
- d) All of the above
Answer: D - Enforce JSON structure/constraints at database level.
249. What is the purpose of the SQL EXPLAIN ANALYZE statement?
- a) Shows actual execution metrics
- b) Estimates query cost
- c) Validates syntax
- d) Tests permissions
Answer: A - PostgreSQL's enhanced query analysis.
250. Which feature enables cross-database ML workflows?
- a) Federated learning
- b) Model sharing
- c) Data virtualization
- d) All of the above
Answer: D - Train models on distributed data without centralization.
251. What is the purpose of the SQL CREATE ASSERTION statement?
- a) Defines multi-table constraints
- b) Creates alerts
- c) Validates backups
- d) Tests performance
Answer: A - Advanced constraint checking (SQL standard feature).
252. Which database provides homomorphic encryption extensions?
- a) PostgreSQL with pg_he
- b) SQL Server with SEAL
- c) Oracle with HE Toolkit
- d) Research prototypes only
Answer: D - Not yet production-ready in major DBMS.
253. What is the purpose of the SQL TRACE() function?
- a) Logs query execution steps
- b) Draws spatial lines
- c) Follows foreign keys
- d) Validates schemas
Answer: A - Detailed performance diagnostics (MySQL/SQLite).
254. Which tool provides database observability dashboards?
- a) Datadog
- b) New Relic
- c) Grafana
- d) All of the above
Answer: D - Visualize metrics/logs/traces from multiple sources.
255. What is the purpose of the SQL ENFORCE CONTRACT clause?
- a) Validates data on write
- b) Checks schema compliance
- c) Tests permissions
- d) Audits changes
Answer: A - Snowflake's data contract implementation.
256. Which database unifies SQL and graph queries?
- a) Neo4j with SQL extensions
- b) SQL Server with Graph
- c) Oracle PGX
- d) All of the above
Answer: D - Query both relational and graph data simultaneously.
257. What is the purpose of the SQL EXPLAIN_JSON() function?
- a) Returns query plans as JSON
- b) Validates JSON syntax
- c) Formats JSON output
- d) Compresses JSON
Answer: A - Machine-readable execution plans (MySQL 8.0+).
258. Which feature enables neural network inference in SQL?
- a) PREDICT_NN()
- b) INFER_MODEL()
- c) RUN_NEURAL_NET()
- d) Implementation-specific
Answer: D - Oracle: PREDICTION, SQL Server: PREDICT, PostgreSQL: pg_ai.
259. What is the purpose of the SQL WATCH statement?
- a) Real-time query streaming
- b) Monitoring locks
- c) Security auditing
- d) Performance tuning
Answer: A - Snowflake's continuous results feature.
260. Which database provides built-in data contracts?
- a) Snowflake
- b) Databricks
- c) Google BigQuery
- d) All of the above
Answer: D - Formalize producer-consumer data agreements.