Which statement best describes a data warehouse?

Question

BlackTom AI · Accepted Answer

A data warehouse is a centralised repository where OLTP data is extracted, transformed (cleaned, summarised) and loaded for analytical use — i.e. "OLTP data is extracted and transformed (e.g. cleaned, summarised) before being stored in a centralised database."

1) Relevant knowledge points and concepts
- OLTP vs OLAP: OLTP systems support transactional operations (inserts/updates), OLAP systems support analytical queries over historical data.  
- ETL: Extract, Transform, Load is the standard process for moving operational data into a warehouse (extraction from sources, transformation for consistency and summarisation, loading into the warehouse).  
- Characteristics of a data warehouse: subject-oriented, time-variant, non-volatile (read-mostly), integrated, optimized for queries and reporting.  
- Schema design: warehouses often use denormalised star/snowflake schemas or aggregated structures for fast queries, not strictly 3NF.

2) Step-by-step reasoning
- Identify purpose: warehouses are built for analytics, not for transactional processing.  
- Determine how data arrives: operational (OLTP) data is typically extracted and then transformed (cleansing, conformance of dimensions, summarisation/aggregation, enrichment) before loading. This transformation differentiates a warehouse from a simple copy.  
- Evaluate options against these facts: the correct description must mention ETL/transformation and centralised storage for analytics.

3) Intermediate steps/details
- Extraction: read from OLTP and external sources.  
- Transformation: deduplicate, convert formats, conform dimensions, compute aggregates.  
- Load: store in centralised schema optimized for reporting.

4) Why the correct answer is correct
Because it explicitly states the ETL/transformation step and centralised storage for analytical use, matching core data-warehouse principles (integrated, time-variant, non-volatile, optimized for querying).

5) Why other options are incorrect
- "3NF" option: implies normalized OLTP-style design; warehouses typically use denormalised/aggregated schemas for performance, not strict 3NF.  
- "Read only copied 'as is'": incorrect because warehouses transform and integrate data rather than copy raw transactional rows unchanged.  
- "Big data database designed for all users": vague and misleading — warehouses are for analytical workloads and BI users; they aren’t simply a generic “big data” store for everyone.

6) Conclusion
The correct answer is: "OLTP data is extracted and transformed (e.g. cleaned, summarised) before being stored in a centralised database," which matches the provided answer.

Which statement best describes a data warehouse?Single choice

Similar Questions

The cafe has a POS, a spreadsheet inventory list, and QuickBooks. Each uses different item categories. A team recommends a data warehouse for better reporting instead of ERP integration. Which critique is strongest?

Which environment is best suited for long-term, cross-department trend analysis?

Online analytical processing (OLAP) involves the analysis of accumulated data by end users.

The data in a data warehouse have which of the following characteristics?

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler