---
title: "Metadata and DW architecture"
subject: "Data Mining"
chapter: 1
key: "semester_7/data_mining:metadata-dw-architecture"
source: https://www.bctengineer.com/q/semester_7/data_mining/metadata-dw-architecture
site: BCT Engineering
---

# Metadata and DW architecture

Data Mining · Chapter 1: Introduction

- Asked in: year not given
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/data_mining/metadata-dw-architecture
- Whole chapter: https://www.bctengineer.com/md/semester_7/data_mining/chapter-1

## Question

What is meta data? Briefly explain the architecture of Data Warehouse.

## Short answer

Metadata is data about data, describing schema, source-to-target mappings, transformation rules, load history, lineage and business definitions. A data warehouse architecture has a bottom tier warehouse server fed by ETL, a middle tier OLAP server, a top tier of front-end tools, and a metadata repository supporting the system.

## Answer

**Metadata** is "data about data". In a warehouse it describes the structure, content, origin and use of data: schema, source-to-target mappings, transformation rules, aggregation rules, load history, data lineage, business definitions and access rights. It is stored in a metadata repository and is used by ETL tools, managers and end users.

**Example**: column `sales_amt` is "bill total in NPR, source POS.BILL.TOTAL, loaded daily".

#### Architecture of a data warehouse
```text
 Operational DBs   External   Flat files
        \             |          /
         v            v         v
     [ Extract - Clean - Transform - Load ]
                      |
                      v
   +----------------------------------------+
   |        DATA WAREHOUSE SERVER           |
   | Detailed data | Summary data | Metadata|
   |   Data marts (dependent)               |
   +----------------------------------------+
                      |
              [ OLAP Server ]
                      |
   Query/report | OLAP/analysis | Data mining tools
```

- **Bottom tier**: warehouse database server (relational), fed by back-end ETL tools (extract, clean, transform, load, refresh) from the operational and external sources. It holds detailed data, summary data, metadata and data marts.
- **Middle tier**: OLAP server (ROLAP, MOLAP or HOLAP) that presents the multidimensional view.
- **Top tier**: front-end tools for query and report, analysis (OLAP) and data mining.
- **Metadata repository** and **monitoring/administration** support the whole system.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is metadata?
   A. Duplicate data
   B. Data about data such as schema, mappings, lineage and transformation rules
   C. Only summary data
   D. Raw backups
   Answer: B. Metadata describes structure, content, origin and use of warehouse data. (Key point: Metadata meaning)

2. What is in the bottom tier?
   A. Front-end query tools
   B. Warehouse database server fed by ETL, holding detailed data, summaries, metadata and data marts
   C. OLAP server
   D. Data mining tools
   Answer: B. The bottom tier is the warehouse database fed by back-end ETL. (Key point: Bottom tier)

3. What is the middle tier?
   A. OLAP server (ROLAP, MOLAP or HOLAP)
   B. Operational databases
   C. Flat files
   D. Reports
   Answer: A. It presents the multidimensional view. (Key point: Middle tier)

4. Which tools are in the top tier?
   A. ETL tools
   B. Query/report, OLAP analysis and data mining front-end tools
   C. Operational DBs
   D. Metadata only
   Answer: B. The top tier is the front end for users. (Key point: Top tier)

## Related in Data Mining

- [Data warehouse architecture and components](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adw-architecture-components) — Data Mining, chapter 1
- [National data warehouse process architecture](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Anepal-national-data-warehouse) — Data Mining, chapter 1
- [Short note: Data marts and metadata](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adatamart-metadata-note) — Data Mining, chapter 1
- [Short note: DW process architecture](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adw-process-architecture-note) — Data Mining, chapter 1
- [Warehouse architecture and three phases](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adw-architecture-three-phases) — Data Mining, chapter 1
- [Kathmandu Mall warehouse architecture](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Akathmandu-mall-warehouse) — Data Mining, chapter 1

## Related in other subjects

- [Data warehouse and data mining](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Adata-warehouse-data-mining) — Information System, chapter 4, asked 2×
- [Hybrid data in big data warehouse](https://www.bctengineer.com/question.md?key=semester_8%2Fbig_data_technologies%3Ahybrid-data-warehouse) — Big Data Technologies, chapter 1