Database Representation-Based Notional Machines

Database Analogy-based notional machines map from a database context to a context that is an analogy students are potentially familiar with. This allows students to reason in familar ways in the analogous space, and to transfer that reasoning to the programming space.

Some representations are handmade (e.g., a diagram drawn on a board) while others are machine-generated (e.g., a visualization produced by a tool).

We collected and organized the following 25 representation-based notional machines:

Database Analogies

Databases Discipline:

Illustrates the purpose of developing a conceptual model.

The purpose of modeling

Symbol	Concept
model	map (abstraction of the real world)

Collected by Xiaoying Tu

Database Analogies

Databases Discipline:

focus on structure

abstraction

Symbol	Concept

Collected by Raja Sooriamurthi

Database Analogies

Databases Discipline:

it clarifies the purpose and value of data modelling

importance of conceptual design (data model) preceding physical implementation, shows the potential for high costs and time delays if design flaws are discovered late in the development lifecycle

Symbol	Concept
Data Model	Blueprint
Database	Constructed Building
Changing Design	Redrawing Lines
Changing Implemented Database	Rebuilding Walls, Electrical, Plumbing

Collected by Yuhan Pan

Database Analogies

Databases Discipline:

helps students understand that a careful modelling can save retrieval efforts through an example close to their everyday experience (specifically tailored to the less represented gender)

motivations for learning data modelling, data structuring, indexing

Symbol	Concept
resources (data)	shoes
selective data access	finding a pair of shoes
metadata (data describing data)	photos of shoes
index	mechanism that speed up search avoiding to look inside all boxes

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

Evokes a visual of how clean and curated the data is

Highlights how clean data is important for traditional systems, but not for MapReduce systems.

Symbol	Concept
traditional data warehouse systems	walled gardens - ingested data is pristine, curated, and has structure.
MapReduce systems process	arbitrarily structured data, whether clean or dirty, curated or not. There is no loading step. This means users can store data first and consider what to do with it later.

Collected by Daphne Miedema

Database Analogies

Databases Discipline:

it clarifies the basic concept of a database as a collection of related information

The fundamental idea of a database as a "set of related information"

Symbol	Concept
Database	Telephone Book

Collected by Yuhan Pan

Database Analogies

Databases Discipline:

Helps readers get a high-level idea of what indexing is and how it can help speeding up queries

The advantage of indexing in speeding up queries

Symbol	Concept
Database table indexing	a book's index

Collected by Xiaoying Tu

Database Analogies

Databases Discipline:

Relates database index to real world students may be familiar with. Note: this is dated for new students

what an index is used for

Symbol	Concept
index	card catalog
file/entry in file	book or other resource

Collected by Martin Goodfellow

Database Analogies

Databases Discipline:

Explains each step of the DB design methodology with a familiar analogy

The steps of a DB design methodology

Symbol	Concept
conceptual design	physical fitness
logical design	strenght training
physical design	speed training

Collected by Laura Farinetti

Database Analogies

Databases Discipline:

Draw on the law of the instrument: "it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail"

The (previous) omnipresence of disk-based row-stores as a storage solution

Symbol	Concept

Collected by Daphne Miedema

Database Analogies

Databases Discipline:

Stresses the similarity with object oriented programming languages

The fact that entities have common properties

Symbol	Concept
entity	object
set of entities	class

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

The concept of a 'fat table' conjures an anthropomorphic image

How tables in a star schema can get bigger than our normal conception of 'big'.

Symbol	Concept

Collected by Daphne Miedema

Database Analogies

Databases Discipline:

Helps readers understand the mechanism of joining more than two tables

The fact that each additional table is joined with the intermediate resulting table, just like the snowball gets bigger when rolling down the hill.

Symbol	Concept
snowball	the "intermediate table" after joining each additional table

Collected by Xiaoying Tu

Database Analogies

Databases Discipline:

Draws parallels to processing as done in relational databases.

How reading from JSON is similar to RDBMS projection

Symbol	Concept
JSON structure	schema
defining what to see at runtime	projection operation
schema on read	relational operation"

Collected by Daphne Miedema

Database Analogies

Databases Discipline:

reduce data redundancy and eliminate modification anomalies, by relating it to a familiar concept from English grammar

highlights the design principle of decomposition

Symbol	Concept
Database Table	Paragraph
Data "Themes"	Paragraph Themes
Normalisation	Reorganising/Breaking up paragraphs

Collected by Yuhan Pan

Database Analogies

Databases Discipline:

familiar concept (book index)

ease of retrieval/indentification

Symbol	Concept

Collected by Raja Sooriamurthi

Database Analogies

Databases Discipline:

helps students understand what data clustering and querying flexibility means through an example close to their everyday experience

Efficiency if access can be predetermined, flexibility for unanticipated access

Symbol	Concept
Data Clustering / Locality of Reference (efficiency)	All Xmas decorations in the same box since they will be needed again at the same time (next Xmas)
Query Flexibility	Off-Season Ornament Hunting (I just need a red bauble and I am still able to get it) [could be related to indexing if it can be anticipated]
Disk	Storage room (basement/garage)

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

Highlights the fact that relational models consist of only one type of building blocks: the relations. This is in contrast to conceptual models which typically consist of different types of building blocks (entities, relationships, multiplicities, inheritance, etc.)

Relational models consist of relations only

Symbol	Concept
Lego bricks	relations

Collected by Xiaoying Tu

Database Analogies

Databases Discipline:

Stresses the idea that relationships connect entities

The connections among the ER model components

Symbol	Concept
Relationship	glue among entities

Collected by Laura Farinetti

Database Analogies

Databases Discipline:

brings similarity with the familiar concept of spreadsheet

the row/column structure

Symbol	Concept
table	spreadsheet

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

helps user understanding ternary (and n-ary) relationships as sets of triples (n-uples)

An instance of the entity might or might not participate to the relationship A instance of the relationship always requires one instance of each related entity

Symbol	Concept
relationship instance	table
entity instance	leg

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

(supposed) familiarity of index cards

How each tuple carries its own (independent) set of data

Symbol	Concept
relational database	filing cabinet

Collected by Daphne Miedema

Database Analogies

Databases Discipline:

helps students understanding the role of external/mixed identifiers referring to person identities (movie character)

how cardinality constraints and external/mixed identifiers for weak entities are related (case of multiple participation to identifyingn relationship)

Symbol	Concept
weak entity instance	person (Mr Robot)
identifier	person's identity

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

helps students understanding the role of external/mixed identifiers referring to person identities (movie character)

how cardinality constraints and external/mixed identifiers for weak entities are related (case of optional participation to identifying relationship)

Symbol	Concept
weak entity instance	person (Jason Bourne)
identifier	person's identity

Collected by Giovanna Guerrini

Database Analogies

Databases Discipline:

helps user understanding the role of external/mixed identifiers referring to person identities issues (Italian book character)

how cardinality constraints and external/mixed identifiers for weak entities are related (should be single and mandatory)

Symbol	Concept
weak entity instance	person (Pirandello's Vincenzo Moscarda)
identifier	person's identity

Collected by Giovanna Guerrini

Analogies Representations Database Representation-Based Database Analogy-Based

A notional machine is a pedagogic device to assist the understanding of some aspect of programs or programming. To something along the lines of A notional machine is a pedagogical tool designed to support the understanding of programs, programming, and other aspects of computing such as databases.

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Database Analogies Notional Machines

What is a representation-based notional machine?

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