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Chapter 2 Flashcards

Data modeling (67 cards)

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1
Q

Data modeling

A

Interactive and progressive process of creating a specific data model for a determined problem domain

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2
Q

Model

A

Abstraction of a more complex real-world object or event

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3
Q

Data model

A

Simple representation of a complex real-world data structures

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4
Q

importance of data models

A

Facilitates communication

Gives various views of the database

Organizes data for various users

Provides an abstraction of the creation of a good database.

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5
Q

Entity

A

Person, place, thing or event about which data will be collected and stored.

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6
Q

Attribute

A

Characteristic of an entity

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7
Q

Relationship

A

Association among entities

One-to-many (1:M, 1..*)

Many-to-many (M:N, ..)

One-to-one (1:1, 1..1)

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8
Q

Constraint

A

Restriction placed on data.
A set of rules that ensures data integrity.

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9
Q

Business rule

A

A brief, precise and unambiguous description of a policy, procedure or principle.

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10
Q

Business rule uses

A

Create and enforce actions within that organisation’s environment (define basic building blocks)

Establish entities, relationships and constraints (distinguishing characteristics of the data).

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11
Q

Sources of business rules

A

Company managers
Policy makers
Department managers
Written documentation
Direct interviews with end users

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12
Q

Reasons for identifying and documenting business rules

A

Standardise company’s view of data

Facilitate communications tool between users and designers

Assists designers

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13
Q

How business rules assist designers

A

Understand the nature, role, scope of data and business processes

Develop appropriate relationship participation rules and constraints

Create an accurate data model

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14
Q

How business rules help with entities and stuff

A

Nouns translate to entities

Verbs translate into relationships among entities

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15
Q

Entity name requirements

A

be descriptive of the objects in the business environment

Use terminology that is familiar to the user

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16
Q

Attribute name

A

Required to be descriptive of the data represented by the attribute

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17
Q

Proper naming

A

Facilitates communication between parties

Promotes self-documentation

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18
Q

Hierarchical Models

A

Developed to manage large amount of data for complex manufacturing projects

Represented by an upside-down tree which contains segments (equivalent of a file system’s record type)

Depicts a set of (1:M) relationships

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19
Q

Network Models

A

Created to represent complex data relationships effectively

Improved database performance and imposed a database standard

Allows a record to have more than one parent

Depicts both 1:1 and M:N relationships

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20
Q

Schema

A

Conceptual organisation of the entire database as viewed by the database administrator

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21
Q

Subschema

A

Portion of the database seen by the application programs that produce the desired information from the data within the database.

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22
Q

Data manipulation language (DML)

A

Environment in which data can be managed and is used to work with the data in the database

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23
Q

Schema data definition language (DDL)

A

Enables the database administrator to define the schema components.

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24
Q

The relational model

A

Produced an “automatic transmission” database that replaced “standard transmission” databases.

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25
The relational model is...
Based on a relation (table) : matrix composed of: Intersecting rows (tuples) and Columns (attributes) Describes a precise set of data manipulation constructs based on advanced mathematical concepts
26
Relational database management system (RDBMS)
Performs basic functions provided by the hierarchical and network DBMS systems Makes the relational data model easier to understand and implement Hides the complexities of the relational data model from the user
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SQL-based relational database application
End user interface: -allows the end user to interact with the data model Collection of tables stored in the database: -each table is independent from another -rows in different tables are related based on common values in common attributes SQL engine -executes all queries
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Entity relationship model:
Graphical representation of entities and their relationships in a database structure
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Entity relationship diagram (ERD)
Uses graphic representations of model database components Entity instance or entity occurrence: rows in the relational table Attributes: describes particular characteristics Connectivity: term used to label the relationship types
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Object-oriented data model
Both data and its relationships are contained ina single structure known as an object
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OODM facts
Object-oriented database management system (OODBMS): based on OODM Object: contains data and their relationships with operations that are performed on it -basic building block of autonomous structures -abstraction of real-world entity Attribute: describes the properties of an object
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Class
A collection of similar objects with shared structure and behaviour organised in a class hierarchy
33
Class hierarchy
Resembles an upside-down tree in which each class has only one parent
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Inheritance
Object inherits methods and attributes of classes above it
35
Unified modelling language (UML)
Describes sets of diagrams and symbols to graphically model a system
36
Extended relational data model (ERDM)
Supports OO features, extensible data types based on classes and inheritance -object/relational database management system
37
Extensible markup language (XML)
manages unstructured data for efficient and effective exchange of structured, semistructured and unstructured data
38
Goals of big data
-find new and better ways to manage large amounts of web and sensor-generated data -provide high performance at reasonable cost
39
Characteristics of big data
-Volume -Velocity -Variety (in structure of data)
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Challenges of big data
-Volume doesn't allow usage of conventional structures -Expensive -OLAP tools proved inconsistent dealing with unstructured data
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New technologies of big data
-Hadoop -Hadoop distributed file system (HDFS) -MapReduce -NoSQL
42
NoSQL databases
-Not based on the relational model -support distributed database architecture -Provide high scalability, high availability and fault tolerance -Support large amounts of sparse data -geared toward performance rather than transaction consistency -provides a broad umbrella for data storage and manipulation
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Advantages of Hierarchical model
-Promotes data sharing -Parent/child relationship promotes conceptual simplicity and data integrity -database security is provided and enforced by DBMS -Efficient 1:M relationships
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Disadvantages of hierarchical model
Requires knowledge of physical data storage characteristics Navigation systems requires knowledge of hierarchical path Changes in structure require changes in all application programs Implementation limitations No data definition Lack of standards
45
Network model advantages
Conceptual simplicity Handles more relationship types Data access is flexible Data owner/member relationship promotes data integrity Conformance to standards Includes data definition language (DDL) and data manipulation language (DML)
46
Network model disadvantages
System complexity limits efficiency Navigational systems yields complex implementation, application development and management Structural changes in all application programs
47
Relational model advantages
Structural independence is promoted using independent tables Tabular view improves conceptual simplicity Ad hoc query is based on SQL Isolates the end user from physical-level details Improves implementation and management simplicity
48
Relational model disadvantages
Requires substantial hardware and system software overhead Conceptual simplicity gives untrained people the tools to use a good system poorly May promote information problems
49
Entity relationship model advantages
Visual modelling yields conceptual simplicity Visual representation makes it an effective communication tool Is integrated with the dominant relational model
50
Entity relationship model disadvantages
Limited constraint representation Limited relationship representation No data manipulation language Loss of information content occurs when attributes are removed from entities to avoid crowded displays
51
Object-oriented model advantages
Semantic content is added Visual representation includes semantic content Inheritance promotes data integrity
52
Disadvantages Object-oriented model
Slow development of standards caused vendors to supply their own enhancements Navigational system Learning curve is steep High system overhead slows transactions
53
NoSQL advantages
high scalability, availability and fault tolerance provided uses low-cost commodity hardware Supports big data key-value model improves storage efficiency
54
NoSQL disadvantages
Complex programming is required There is no relationship support There is no transaction integrity support In terms of data consistency, it provides an eventually consistent model
55
Data abstraction
Is the reduction of a particular body of data to a simplified representation of the whole Abstraction, in general, is the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics
56
End user's view of the data environment
People who use the application programs to manipulate the data and generate information
57
ER diagrams are used to represent the external views
External schema: specific representations of an external view
58
Conceptual model
Represents a global view of the entire database by the entire organisation
59
Conceptual schema
Basis for the identification and high-level descrpiton of data objects
60
Logical design
task of creating a conceptual data model
61
Conceptual model advantages
Macro-level view of data environment Software and hardware independent
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The internal model
Representing database as seen by the DBMS mapping conceptual model to the DBMS
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Internal schema
Specific representation of an internal model, using the database constructs supported by the chosen database
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Logical independence
Changing internal model without affecting the conceptual model
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Hardware independent
Unaffected by the type of computer on which the software is installed
66
The Physial model
Operates at lowest level of abstraction -describes the way data are saved on storage media such as magnetic, solid state or optical media Requires the definition of physical storage and data access methods -software and hardware dependent Relational model aimed at logical level -does not require physical-level details Physical independence: changes in physical model do not affect internal model
67

CMPG 311 (7 decks)

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