Week 1 Flashcards
Relational database system
Structured, (Operational workload,(backing, online store)
So what we want here is to build systems, data processing systems,
data management systems that can cope with the
volume,
velocity and variety aspects of the big data
NoSQL Graph doc, key-value stores
Unstructured data (highly available systems
Hadoop, Spark
For analytics over massive scale data
What kind of software should be used if one needs to store data online, make certain parts of it accessible by different user types, and searchable?
Database Management Software
What is a characteristic of big data?
Data comes from different sources in Different formats
What is a database
A very large integrated collection of data
What does a database do?
Models relationships between these entities
Three parts of a database management system (DBMS)
1) Store data
2) Retrieve Data
3) Manage Data
6 Benefits of DBMS
1) Data Independence
2) Efficient Data Access
3) Data Integrity and Security
4) Data Administration
5) Concurrent Access and Recovery
6) Reduced App Development Time
data independence
Isolate the user of the system from how the data is managed ad organized.
The person who’s building the application doesn’t need to know anything
about how the data is stored, how the data is organized inside the database.
All they care about is, again, the application and the database system
takes care of everything related to the organization of the data,
everything related to the performance, the scalability issues.
efficient data access
So efficient data access means that if the application developer doesn’t have a database management system. Then you need to take care of how to, for example, index the data or how to efficiently retrieve the data from where it’s stored. And this is again a lot of burden on the user. So the database management system releases or
carries that burden and the user doesn’t need to do it
Data Administration
And data administration means that you have just one location that you store the data in. And you have one portal to allow for an administrator
Concurrent Access and Recovery
f you have multiple users using the data at the same time, you need to allow for concurrent access.
So concurrent access, the database management systems allow users to concurrently access and run transactions against the database
Data Integrity and Security
So a database management systems takes care of how to secure the data stored in the database.
So we have heard recently of several data breaches like the Equifax data breach, or that happens sometimes. And if you have a really good database management system,
it takes care of the data security itself.
Reduced App Development Time
So if you have a system that allows you to, to give you the efficient data access, it has one place for secure and integrated data, and also data independence.
The application developer all, what he or
she needs to focus on is just the logic of their own application instead of focusing on the scalability, efficiency, security of the database. So you just focus on the logic of the application.
What does data independence mean for a DBMS?
Not required to know how the data in the application is stored
What is a data model
A data model is a collection of concepts that describe the data.
What is a schema
Is a description of the data a model
What is an example of a data model
So the most widely used data model in database systems is the relational model
relations =
table
Each column represents
And each column represent an attribute of this entity
What is the relationship for the number of physical schemas to logical schemas in a DBMS?
1) n:1
2) 1:1
3) 1:n
2) 1:1
Three types of schema
1) physical schema - The way the data is stored and organized
2) conceptual schema - how the data is logically represented (like relational model )
3) external schema / views - multiple external schemas in a database (collect info from different tables)
What is logical data independence?
protects the user or
the application on top of the database from changes in the logical schema or
the logical structure of the data.
What is physical data independence,
Protects the application
from changes in the physical schema or the physical structure of the data
What is the most widely used data model today?
Relational Model
Which of the following is true about data schemas?
There may be multiple external schemas for a given database
Database design - Phase 1
Requirement Analysis
Database design - Phase 2
Conceptual Database Design (draw the database_
Database design - type of diagram
(ER) entity relationship model
Database design - Phase 3
Logical Database Design
In the example, what are the two entities in the company database?
1) Dept, Employee
2) Dept, Budget
3) Employeem, SSN
1) Dept, Employee
In the example, what are the two entities in the company database?
1) Dept, Employee
2) Dept, Budget
3) Employeem, SSN
1) Dept, Employee
3 types of relationships
1) 1 to 1
2) 1 to Many
3) Many to Many
Weak Entities (ER)
Weak Entities can be identified uniquely only by considering the primary key of another entity (owner)
Weak Entities (ER)
Weak Entities can be identified uniquely only by considering the primary key of another entity (owner)
Example of Weak Entities (ER)
Family of dependents depends in a work database
Rules of Weak Entities (ER)
1) must participate in a one-to-many relationship with a stronger entity.
2) a weak entity must have total participation in the relationship with the stronger entity
In the example, can dependents be a primary key?
No, because it is a weak entity and must participate in relationship with employees.
