Chapter 2: Data Models

Object/Relational Database Management System (O/R DBMS)

A DBMS based on the extended relational model (ERDM). The ERDM, championed by many relational database researchers, constitutes the relational model's response to the OODM. This model includes many of the object-oriented model's best features within an inherently simpler relational database structure.

Network Model

A data model standard created in the late 1960s that represented data as a collection of record types and relationships as predefined sets with an owner record type and a member record type in a 1:M relationship.

Extensible Markup Language (XML)

A meta-language used to represent and manipulate data elements. Unlike other markup languages, XML permits the manipulation of a document's data elements. XML facilitates the exchange of structured documents such as orders and invoices over the Internet. standard for the efficient and effective exchange of structured, semistructured, and unstructured data. XML was designed to describe data and to focus on what data is. XML allows the author to define his own tags and his own document structure. XML will be used to structure and describe the Web data,

Class Diagrams

Are used to represent data and their relationships within the larger UML object-oriented system's modeling language.

Object-Oriented Database Management System

Data management software used to manage data in an object-oriented database model.

American National Standards Institute (ANSI) Standards Planning and Requirements Committee (SPARC)

Defined a framework for data modeling based on degrees of data abstraction. The resulting ANSI/ SPARC architecture defines three levels of data abstraction: external, conceptual, and internal.

Data Manipulation Language (DML)

Defines the environment in which data can be managed and is used with the data in the database. computer languages including commands permitting users to manipulate data in a database. This manipulation involves inserting data into database tables, retrieving existing data, deleting data from existing tables and modifying existing data. DML is mostly incorporated in SQL databases.

Subschema

Defines the portion of the database "seen" by the application programs that actually produced the desired information from the data within the database.

Internal Schema

Depicts a specific representation of an internal model, using the database constructs supported by the chosen database. the internal schema is expressed using SQL, the standard language for relational databases.

Business Rule

Is a brief, precise, and unambiguous description of policy, procedure, or principle within a specific organization.

Attribute

Is a characteristic of an entity.

Problem Domain

Is a clearly defined area within the real-world environment, with a well-defined scope and boundaries that will be systematically addressed.

Entity Set

Is a collection of like entities. as a collection of three agents (entities) in the AGENT entity set.

Key-Value

Is a data model based on a structure composed of two data elements: a key and a value, in which every key has a corresponding value or set of values.

Unified Modeling Language (UML)

Is a language based on OO concepts that describes a set of diagrams and symbols you can use to graphically model a system.

NoSQL

Is a large-scale distributed database system that stores structured and unstructured data in efficient ways.

Relation

Is a matrix composed of intersection rows and columns

Entity

Is a person, place, thing, or event about which data will be collected and stored.

Data Model

Is a relatively simple representation, usually graphical, of more complex real-world data structures.

Relational Diagram

Is a representation of the relational database's entities, the attributes within those entities, and the relationships between those entities. the relational diagram shows the connecting fields (in this case, AGENT_CODE) and the relationship type, 1:M.

Contstraint

Is a restriction placed on the data

External Schema

Is a specific representation of an external view.

MapReduce

Is an open source application programming interface that provides fast data analytics services.

Tuple

Is each row in a relation.

Hadoop Distributed File System (HDFS)

Is highly distributed, fault-tolerant file storage system designed to manage large amounts of data at high speeds.

Inheritance

Is the ability of an object within the class hierarchy to inherit the attributes and methods of the classes above it.

Schema

Is the conceptual organization of the entire database as viewed by the database administrator.

Internal Model

Is the representation of the database as "seen" by the DBMS. The internal model requires the designer to match the conceptual model's characteristic and constraints to those of the selected implementation model.

Connectivity

Is used by the ER model to label the relationship types. A relationship describes a constraint on the connection of the associated entity occurrences in the relationship. Values for connectivity are either "one" or "many."

Relational Model

It is a mathematical concept known as a relation.

Relational Database Management Systems

It performs the same the basic functions provided by the hierarchical and network DBMS systems. a type of database management system (DBMS) that stores data in the form of related tables

Conceptual Model

It represents a global view of the entire database by the entire organization. Conceptual model is independent of both software and hardware.

Software Independence

Means that the model does not depend on the DBMS software used to implement the model.

Hardware Independence

Means that the model does not depend on the hardware used in the implementation of the model.

Eventual Consistency

Means that updates to the database will propagate through the system and eventually all data copies will be consistent.

Logical Design

Refers to the task of creating a conceptual data model that could be implemented in any DBMS.

Class Hierarchy

Resembles an upside-down tree in which each class has only one parent.

SQL-based relational database application involves three parts:

The end-user interface. Basically, the interface allows the end user to interact with the data (by automatically generating SQL code). Each interface is a product of the software vendor's idea of meaningful interaction with the data. You can also design your own customized interface with the help of application generators that are now standard fare in the database software arena. • A collection of tables stored in the database. In a relational database, all data are perceived to be stored in tables. The tables simply "present" the data to the end user in a way that is easy to understand. Each table is independent. Rows in different tables are related by common values in common attributes. • SQL engine. Largely hidden from the end user, the SQL engine executes all queries, or data requests. Keep in mind that the SQL engine is part of the DBMS software. The end user uses SQL to create table structures and to perform data access and table maintenance. The SQL engine processes all user requests—largely behind the scenes and without the end user's knowledge.

Semantic Data Model

The first of a series of data models that more closely represented the real world, modeling both data and their relationships in a single structure known as an object.

Data Definition Language (DDL)

Use these statements to create, alter, or drop data structures in a database. Enables the database administrator to define the schema components.

Logical Independence

When you change the internal model without affecting the conceptual model. the internal model depends on specific database software, it is said to be software dependent. Therefore, a change in the DBMS software requires that the internal model be changed to fit the characteristics and requirements of the implementation database model.

Physical Independence

When you change the physical model without affecting the internal model. Therefore, a change in storage devices or methods and even a change in operating system will not affect the internal model.

Entity Relationship (ER) model (ERM)

easier to examine structures graphically than to describe them in text, database designers prefer to use a graphical tool in which entities and their relationships are pictured.

What are the three relationships used by Data Models?

1. One-to-Many 2. Many-to-Many 3. One-to-One

Object-Oriented Data Model (OODM)

A data model whose basic modeling structure is an object.

Entity Instance or Entity Occurrence

Is each row in the relational table

Segment

Is the equivalent of a file system's record type.

the basic characteristics of Big Data databases: ( 3 Vs)

1. volume - amount of data being stored 2. velocity - speed at which data has grown, and the need to process it quickly 3. variety - data being collect comes in multiple different data formats

Entity Relationship Diagram (ERD)

A diagram that depicts an entity relationship model's entities, attributes, and relations. ER models are normally represented in an entity relationship diagram (ERD), which uses graphical representations to model database components.

Extended Relational Data Model (ERDM)

A model that includes the object-oriented model's best features in an inherently simpler relational database structural environment.

Client Node

Acts as the interface between the user application and the HDFS

Object

An abstract representation of a real-world entity that has unique identity, embedded properties, and the ability to interact with other objects and itself.

Relationship

Describes an association among entities

Sparse Data

For cases in which the number of attributes is very large but the number of actual data instance is low. NoSQL supports very large amounts of sparse data. NoSQL databases can handle very high volumes of data.

Method

In the object-oriented data model, a named set of instructions to perform an action. Methods represent real-world actions, and are invoked through messages. Methods define an object's behavior.

Hadoop

Is a Java base, open source, high speed, fault-tolerant distributed storage computational framework.

External Model

Is the end users' view of the data environment. The term end users refers to people who use he application programs to manipulate the data and generate information.

Physical Model

Operates at the lowest level of abstraction, describing the way data are save on storage media such as magnetic, solid state, or optical media.

Big Data

Refers to a movement to find new and better ways to manage large amounts of web and sensor-generated data and drive business insight from it, while simultaneously providing high performance and scalability at a reasonable cost.

Data Modeling

Refers to the process of creating a specific data model for a determined problem domain.

Neme Node

Stores all the metadata about the file system

Data Node

Stores fixed-size data blocks