---
title: "DMQL; transactional vs warehouse database"
subject: "Data Mining"
chapter: 2
key: "semester_7/data_mining:dmql-transactional-vs-dw"
source: https://www.bctengineer.com/q/semester_7/data_mining/dmql-transactional-vs-dw
site: BCT Engineering
---

# DMQL; transactional vs warehouse database

Data Mining · Chapter 2: Data Pre-processing

- Asked in: year not given, 2+3+5 marks; year not given
- Video: [Topic1 Data Mining Task Primitives](https://www.youtube.com/watch?v=--wDm9lwVME) — Philomina Simon
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/data_mining/dmql-transactional-vs-dw
- Whole chapter: https://www.bctengineer.com/md/semester_7/data_mining/chapter-2

## Question

What is DMQL? Where is it applicable? Differentiate between Transactional databases with Data warehouse databases.

## Short answer

DMQL is a SQL-based data mining query language for specifying mining tasks and defining warehouse schemas. It applies to ad hoc mining (characterisation, association, classification, clustering) and to defining star/snowflake/constellation schemas. Transactional databases store current detailed normalised operational data; data warehouses store historical summarised dimensional data for analysis.

## Answer

#### DMQL
**DMQL (Data Mining Query Language)** is a query language proposed by Han et al. (in the DBMiner system) for specifying data mining tasks and for defining data warehouses. It is based on SQL. Its main parts are:
- the task-relevant data (`use database`, `from`, `where`),
- the kind of knowledge to mine (`mine characteristics`, `mine associations`, `mine classification`),
- background knowledge (concept hierarchies),
- interestingness thresholds (`with support threshold`, `with confidence threshold`),
- presentation of the discovered patterns.

It also has commands to define warehouse schemas: `define cube` and `define dimension`.

Example:
```text
use database sales_db
mine associations as buying_habits
matching P(X: customer, W) ^ Q(X, Y) => buys(X, Z)
from sales
with support threshold = 2%
with confidence threshold = 60%
```

#### Where it is applicable
- Specifying and running ad hoc mining tasks (characterisation, association, classification, clustering).
- Defining data warehouse schemas (star, snowflake, constellation) and cubes.
- As a standard interface between mining front ends and mining engines; it lets the user interact with the system and refine the task.

#### Transactional database vs data warehouse
| Point | Transactional database | Data warehouse |
|---|---|---|
| Purpose | Daily operations (OLTP) | Analysis and decision support |
| Data | Current, detailed | Historical, summarised |
| Design | Normalised ER | Dimensional (star/snowflake) |
| Updates | Frequent | Periodic load, read-mostly |
| Queries | Short, simple | Complex, aggregate |
| Users | Clerks, thousands | Managers, analysts |
| Size | MB to GB | GB to TB |

## Check yourself

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

1. What is DMQL?
   A. A tool for normalising relational tables
   B. A language only for drawing ER diagrams
   C. An SQL-based Data Mining Query Language for specifying mining tasks and defining warehouses
   D. A compression algorithm for warehouses
   Answer: C. DMQL is based on SQL and used to specify mining tasks and define warehouse schemas. (Key point: What DMQL is)

2. Which is a main part of a DMQL mining task specification?
   A. The primary key of a table
   B. The disk block size
   C. Backup schedule
   D. Interestingness thresholds such as support and confidence
   Answer: D. A DMQL task specifies task-relevant data, kind of knowledge, background knowledge, thresholds and presentation. (Key point: DMQL parts)

3. Where is DMQL applicable?
   A. Specifying ad hoc mining tasks and defining warehouse schemas/cubes
   B. Only in transaction processing
   C. Only for hardware configuration
   D. Only for sorting files
   Answer: A. It serves as an interface for mining tasks and defines star, snowflake and constellation schemas. (Key point: DMQL applicability)

4. How do updates differ between the two?
   A. Transactional DB: read-mostly; warehouse: frequent updates
   B. Transactional DB: frequent updates; warehouse: periodic load, read-mostly
   C. Both are updated continuously
   D. Neither is ever updated
   Answer: B. A warehouse is loaded periodically and mostly read, unlike a transactional database. (Key point: Transactional DB vs warehouse)

## Related in Data Mining

- [Data warehouse vs database](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adw-vs-database) — Data Mining, chapter 1
- [Where data mining is applicable](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adm-areas-applicable) — Data Mining, chapter 1
- [Data warehouse, data mart and need](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Awarehouse-datamart-need) — Data Mining, chapter 1
- [OLAP vs OLTP; schema modeling; star DMQL](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Aolap-oltp-schema-star-dmql) — Data Mining, chapter 2
- [DW characteristics vs operational database](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Adw-characteristics-vs-operational) — Data Mining, chapter 1
- [RDBMS vs DW database; DW terms](https://www.bctengineer.com/question.md?key=semester_7%2Fdata_mining%3Ardbms-vs-dw-terms) — 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×
- [Column vs row-oriented NoSQL databases](https://www.bctengineer.com/question.md?key=semester_8%2Fbig_data_technologies%3Acolumn-oriented-nosql-row-oriented) — Big Data Technologies, chapter 4
- [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
- [SQL: create and use bank database](https://www.bctengineer.com/question.md?key=semester_6%2Fdatabase_management_system%3Asql-create-database-bank) — Database Management System, chapter 3