Data Modeling and Schema Design Flashcards
6 cards from real Data Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Data Modeling and Schema Design flashcards as text
Which technique stores multiple versions of a record with start and end dates to track historical changes?
Answer: Type 2 SCD
Type 2 SCD adds a new row for each change with effective start/end dates, preserving full history of dimension attribute changes.
In a columnar storage format like Parquet, data is physically stored:
Answer: Column by column, enabling better compression and analytical scans
Columnar formats store all values of a column together, enabling better compression and allowing analytic queries to scan only the needed columns.
What is the primary advantage of using a wide table (denormalized) in analytical workloads?
Answer: Fewer joins required at query time, improving performance
Wide denormalized tables pre-join data, eliminating costly join operations at query time and improving analytical query performance.
Which data modeling approach uses nodes and edges to represent complex many-to-many relationships, ideal for social networks or recommendation engines?
Answer: Graph modeling
Graph modeling represents entities as nodes and relationships as edges, naturally expressing complex interconnected data for traversal queries.
What is an 'outrigger' in dimensional modeling?
Answer: A secondary dimension table referenced by another dimension table
An outrigger is a secondary dimension table that a primary dimension table references, similar to snowflaking but typically for date or classification attributes.
In Apache Iceberg table format, what enables time-travel queries on large datasets?
Answer: Immutable snapshot-based metadata and manifest files
Iceberg uses immutable snapshots where each write creates a new snapshot, allowing queries to reference past snapshots for time-travel without data copies.