LFC Data Management 3 — Questions and Answers
Question 1: Which file format is the default storage format for Delta Lake tables?
- ORC
- Avro
- Parquet (Correct answer)
- CSV
Correct answer: Parquet
Delta Lake stores data as Parquet files and adds a transaction log layer on top to provide ACID guarantees.
Question 2: A business analyst needs read access to a specific table in Unity Catalog but should not see other tables in the same schema. What is the recommended approach?
- Grant SELECT on the entire schema
- Grant SELECT on just that specific table (Correct answer)
- Clone the table to a separate catalog
- Disable row-level security
Correct answer: Grant SELECT on just that specific table
Unity Catalog supports fine-grained privilege grants at the table level, so you can grant SELECT on a single table without exposing the whole schema.
Question 3: What is the role of 'data quality rules' in a medallion architecture?
- They determine which cloud storage bucket receives raw data
- They enforce checks that data must pass before advancing to the next layer (Correct answer)
- They automatically generate schema for incoming JSON files
- They compress Parquet files to reduce storage costs
Correct answer: They enforce checks that data must pass before advancing to the next layer
Data quality rules (constraints, expectations) validate correctness, completeness, and conformity, acting as gates between Bronze, Silver, and Gold layers.
Question 4: Which Delta Lake command consolidates many small Parquet files into fewer, larger files to improve query performance?
- VACUUM
- ANALYZE
- OPTIMIZE (Correct answer)
- REORG
Correct answer: OPTIMIZE
OPTIMIZE compacts small files into larger, more efficient Parquet files, reducing the overhead of reading thousands of tiny fragments.
Question 5: In the context of lakehouse data management, what does PII stand for and why is it significant?
- Partitioned Index Information — used for query optimization
- Personally Identifiable Information — subject to privacy regulations requiring controlled access (Correct answer)
- Primary Ingestion Interface — the entry point for raw data
- Pre-Indexed Integration — a catalog search acceleration feature
Correct answer: Personally Identifiable Information — subject to privacy regulations requiring controlled access
PII (Personally Identifiable Information) includes data that can identify an individual; regulations like GDPR and CCPA mandate strict access controls and retention policies.
Question 6: What does enabling Change Data Feed (CDF) on a Delta table allow downstream processes to do?
- Automatically partition the table by ingestion date
- Read only the rows that changed since the last read rather than the full table (Correct answer)
- Convert the table to streaming-only mode
- Enforce schema evolution without manual approval
Correct answer: Read only the rows that changed since the last read rather than the full table
CDF exposes a change log of inserted, updated, and deleted rows, enabling efficient incremental processing without full table scans.
Question 7: Which Unity Catalog securable object stores files (images, CSVs, ML models) in cloud storage while enforcing access controls?
- External Location
- Volume (Correct answer)
- Share
- Credential
Correct answer: Volume
Volumes provide governed access to non-tabular files in cloud object storage, with Unity Catalog enforcing permissions just like tables.
LFC Data Management 3
Which file format is the default storage format for Delta Lake tables?