DA0-002 Data Concepts and Environments Practice Question
A data engineer is ingesting streaming data from a fleet of delivery vehicles. Each vehicle sends GPS coordinates, speed, and timestamp every second. The engineer needs to store this data for real-time dashboards and also retain it for long-term historical analysis. Which data storage approach best balances real-time access and cost-effective long-term retention?
⚠ Common exam trap
The trap here is choosing a single storage technology for both real-time and archival needs, ignoring that a hybrid approach is often required to balance performance and cost.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a time-series database for recent data and archive to object storage
A time-series database handles high-velocity timestamped writes and enables fast real-time queries for dashboards. Archiving older data to object storage reduces cost while preserving durability for historical analysis. Row-based relational databases, key-value stores without indexes, and in-memory caches each fail to balance real-time performance with cost-effective long-term retention for streaming vehicle telemetry.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store all data in a relational database with row-based storage
Why it's wrong here
A row-based relational database handles transactional workloads well but becomes expensive and slow for high-velocity streaming writes and large-scale analytical scans. Storing every second of GPS data for a fleet would quickly overwhelm the system, and row-based storage is inefficient for aggregations. It does not provide the cost-effective long-term retention or real-time dashboard performance needed.
- ✗
Keep all data in memory using an in-memory cache
Why it's wrong here
In-memory caches provide extremely low latency but are expensive per gigabyte and volatile unless persisted. Retaining months or years of vehicle telemetry in memory is cost-prohibitive and risks data loss on failure. This approach cannot provide the durable long-term retention required for historical analysis, making it unsuitable for the described balance of real-time and archival needs.
- ✓
Use a time-series database for recent data and archive to object storage
Why this is correct
A time-series database is optimized for high-ingest, timestamped data and supports fast real-time queries for dashboards. Archiving older data to object storage (e.g., S3) provides low-cost, durable long-term retention. This hybrid approach balances performance and cost, allowing recent data to be queried quickly while historical data remains accessible for batch analysis.
- ✗
Store all data in a key-value store with no secondary indexes
Why it's wrong here
A key-value store offers fast lookups by key but lacks the query flexibility needed for time-range scans and aggregations on GPS data. Without secondary indexes, retrieving data for dashboards or historical analysis would require full scans, which is inefficient at scale. It also does not provide the cost-effective archival tiering that object storage offers.
Go deeper
Related to this question
About these practice questions
This DA0-002 question is part of Courseiva's 1,004-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This DA0-002 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DA0-002 exam.