Data architecture
25 bites tagged Data architecture: interview questions with model answers, and 60-second explainers.
Compare data warehouses and data lakes. How does a lakehouse merge benefits?
Tests schema tradeoffs. Warehouses enforce ACID for BI but cost more; lakes store raw cheaply but lack governance. Lakehouses add ACID metadata on object storage to unify ML and BI.
Design a cross-product user journey data architecture
This tests portfolio-scale data platform design. A strong answer outlines streaming event ingestion, a unified identity graph, consent-aware PII vaults, and schema registries with data contracts.
Design real-time usage-based billing data architecture
Tests whether you can guarantee exactly-once billing at scale without data loss. Strong answers cover idempotent Kafka ingestion, ClickHouse aggregation, reconciliation, and audit trails. Red flag: claiming exactly-once instead of at-least-once dedup.
When is streaming better than batch, and what are its infrastructure challenges?
Tests if you separate low-latency decisions from analytics and know ops pain. Good answer: fraud detection vs batch; cite exactly-once, state recovery, backpressure, schema drift. Red flag: calling streaming faster batch while ignoring backpressure or state.
Describe the difference between ETL and ELT and when to choose each
Tests transform timing and compute location. ETL cleans data before loading via external engines; ELT loads raw data first, then transforms in the warehouse. Pick ETL when pre-load cleansing is needed, ELT when warehouse compute is cheaper.
Design a headless CMS model for brand voice metadata and API usage
Structured content beyond page blobs. Strong answers validate tone, context, and character limits in the CMS; expose them via API filters; and let clients render context-aware components.
Propose a technical architecture for a centralized Metrics Layer or Metrics Store
This tests your ability to decouple metric semantics from storage and query tools. A strong answer outlines a semantic layer with versioned definitions, a query API, and enforced downstream consumption.
Enforce GDPR's Right to be Forgotten Across a Complex Architecture
This tests your design of a verifiable, async deletion workflow. A strong answer proposes a central index metastore, an orchestrated workflow (e.g., Step Functions) for deletion, and an auditing layer.
Propose a technical architecture for a centralized Metrics Layer.
This tests your grasp of data governance and semantic layers. A great answer outlines a system with a central definition store (e.g., YAML in Git), a query engine, and an API, ensuring all teams get consistent metric results.
Design a Fast, Multi-Dimensional Analytics Dashboard
This tests your grasp of data warehousing trade-offs for analytics. A great answer compares OLAP cubes (fast, pre-computed) vs. columnar DBs (flexible, real-time), then proposes a hybrid model.
Data Warehouse vs. Data Lake vs. Lakehouse
Tests your grasp of modern data architectures. A great answer defines warehouses (structured, schema-on-write) and lakes (raw, schema-on-read), then explains how a lakehouse adds ACID transactions and governance on top of a lake.
Design a Privacy-Compliant Analytics Architecture
This tests your ability to balance data utility with strict privacy controls. A great answer outlines a central governance layer, dynamic masking, and purpose-based access tied to auditable logs.
Trade-offs: Bundled vs. Warehouse-Native Product Analytics
This tests your grasp of modern data stack architecture. A great answer weighs trade-offs in data control, cost, query flexibility, and team capabilities. A red flag is ignoring total cost of ownership and engineering overhead for a warehouse-native setup.
Design a Centralized Metrics Layer
This tests your grasp of data governance and creating a single source of truth. A good answer defines a semantic layer between the data warehouse and BI tools, centralizing metric definitions in code.
How would you architect a fast, multi-dimensional analytics dashboard?
This tests your grasp of analytics architectures and trade-offs between pre-computation and real-time querying. A great answer clarifies needs, then proposes a hybrid model using an OLAP cube for core metrics and a columnar store for ad-hoc queries.
Design a Scalable Data Governance Framework
This tests your grasp of decentralized data governance (Data Mesh). A great answer outlines four principles: domain ownership, data as a product, a self-serve platform, and federated computational governance.
Compare a data warehouse, data lake, and lakehouse
Tests your grasp of data architectures for BI vs. ML workloads. Contrast warehouses (structured) and lakes (raw), then explain how a lakehouse adds ACID/schema features to a lake's storage. A red flag is confusing schema-on-write vs. schema-on-read.
Data Lake vs. Data Warehouse: Raw vs. Refined Data
A data lake is a vast pool of raw data; a data warehouse is a library of refined data ready for analysis. Lakes store everything for future ML or data science; warehouses power BI reporting on clean metrics.
Schema-on-Read vs. Write: Pay for Structure Now or Later?
Schema-on-Write pays to structure data upfront for fast, consistent reads. Schema-on-Read defers this cost to query time for flexible ingestion. This choice underpins relational databases (write) vs. data lakes (read). The footgun is creating a data swamp.
Windowing: Taming Infinite Data Streams
Windowing chops infinite data streams into finite chunks for aggregation, like counting clicks per minute. It's essential for real-time dashboards, fraud detection, and IoT sensor analysis. The main footgun is mishandling late data by confusing event time vs.
Data Mesh: From Central Data Lake to Distributed Ownership
Data Mesh decentralizes data ownership, moving it from a central team to the business domains that create it. This approach, like microservices for data, is for orgs where a monolithic data lake has become a bottleneck.
Single Source of Truth (SSOT): One Place for Every Fact
A Single Source of Truth (SSOT) means every piece of data has one authoritative home. Instead of emailing report_v3.docx, you share one link. This prevents conflicts between billing and shipping data.
Master Data Management (MDM): The Single Source of Truth
Master Data Management (MDM) creates a single source of truth for core business entities. It's used when departments have conflicting data (e.g., 'ACME Inc.' vs 'Acme Corp').
Data Lakehouse: The 'Lake' Foundation
A data lake is a central repository that stores all your data—structured or raw—in its original format. It's used to hold raw source system copies, sensor data, and social feeds for later analysis, but can become a messy "data swamp" without governance.
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