Database Systems: Client-Server Model
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Questions and Answers

What is the daily amount of videos watched on YouTube?

  • 500 million videos
  • 100 million videos (correct)
  • 200 million videos
  • 50 million videos

    • What is the daily amount of videos added to YouTube?

  • 30,000 videos
  • 50,000 videos
  • 80,000 videos
  • 65,000 videos (correct)

    • What is the minimum amount of terabytes of videos on YouTube?

  • 45 terabytes (correct)
  • 30 terabytes
  • 40 terabytes
  • 50 terabytes

    • What is the amount of extra information YouTube processes daily?

    <p>6 petabytes</p> Signup and view all the answers

    What is the ranking of NERSC in the world?

    <p>No. 1</p> Signup and view all the answers

    What is the amount of data stored by NERSC?

    <p>2.8 petabytes of data</p> Signup and view all the answers

    What is the ranking of YouTube in the list of data storage?

    <p>No. 7</p> Signup and view all the answers

    How many active customers does Amazon have?

    <p>59 million active customers</p> Signup and view all the answers

    What is the main purpose of an Enterprise Resource Planning (ERP) system?

    <p>To hold all enterprise functions such as manufacturing and finance</p> Signup and view all the answers

    What is the primary function of a data warehouse?

    <p>To integrate data from various operational databases</p> Signup and view all the answers

    What is the advantage of using a data warehouse in an organization like Harrah's?

    <p>It helps to understand customer behavior</p> Signup and view all the answers

    What is the primary difference between an operational database and a data warehouse?

    <p>The purpose of the data</p> Signup and view all the answers

    What is an example of a use case for an Enterprise Data Warehouse (EDW) mentioned in the content?

    <p>Identifying sales anomalies</p> Signup and view all the answers

    What is the size of the largest data warehouse mentioned in the content?

    <p>12.1 petabytes (PB)</p> Signup and view all the answers

    What is a characteristic of a database mentioned in the history of databases?

    <p>It is a collection of connected records</p> Signup and view all the answers

    What is the advantage of using an Enterprise Data Warehouse (EDW) in an organization like Wal-Mart?

    <p>It helps to identify sales anomalies</p> Signup and view all the answers

    What is a fundamental requirement of a relation in a relational model?

    <p>Every attribute value must be atomic</p> Signup and view all the answers

    What is the primary purpose of a primary key in a relation?

    <p>To uniquely identify each row in a relation</p> Signup and view all the answers

    What is true about the order of columns in a relation?

    <p>It is irrelevant but can be used for indexing</p> Signup and view all the answers

    What is the difference between a simple key and a composite key?

    <p>A simple key is a single field, while a composite key is more than one field</p> Signup and view all the answers

    What is the purpose of a foreign key in a relation?

    <p>To establish a relationship between two relations</p> Signup and view all the answers

    What is a characteristic of a relation in a relational model?

    <p>Every row must be unique</p> Signup and view all the answers

    What is an example of a primary key?

    <p>EmployeeID</p> Signup and view all the answers

    What is a requirement for a relation to be considered a valid relation?

    <p>Every attribute value must be atomic</p> Signup and view all the answers

    What is the purpose of Referential Integrity in a relational database?

    <p>To ensure that foreign key values match primary key values in another relation or are null</p> Signup and view all the answers

    What happens if you try to delete a customer who has placed orders in the ORDER relation, and the Delete Rule is set to Restrict?

    <p>The customer is not deleted, and their orders remain</p> Signup and view all the answers

    What happens if you try to delete a customer who has placed orders in the ORDER relation, and the Delete Rule is set to Cascade?

    <p>The customer and their orders are deleted</p> Signup and view all the answers

    What happens if you try to delete a customer who has placed orders in the ORDER relation, and the Delete Rule is set to Set-to-Null?

    <p>The customer is deleted, and their orders are set to null</p> Signup and view all the answers

    Can you delete the city Kabul if the CountryCode in City_T does not match any Code in Country_T?

    <p>No, the city Kabul cannot be deleted because it does not match any Code in Country_T</p> Signup and view all the answers

    What is the purpose of the Delete Rule in Referential Integrity?

    <p>To control the deletion of parent and dependent rows</p> Signup and view all the answers

    What happens if you try to delete the Country Afghanistan and the Delete Rule of this Foreign Key is set to Cascade?

    <p>The Country Afghanistan and all related cities are deleted</p> Signup and view all the answers

    Why is the Set-to-Null Delete Rule not allowed for weak entities?

    <p>Because it would cause the entity to lose its identity</p> Signup and view all the answers

    What type of databases are used by a single user?

    <p>Personal databases</p> Signup and view all the answers

    What is a characteristic of workgroup databases?

    <p>Each member of the workgroup has a computer linked by a network</p> Signup and view all the answers

    What is typically found on the client computer in a workgroup database?

    <p>The user interface application</p> Signup and view all the answers

    What type of databases support the entire organization?

    <p>Enterprise applications</p> Signup and view all the answers

    What is an example of a large database?

    <p>The World Data Center for Climate</p> Signup and view all the answers

    Where is the business logic typically found in a workgroup database?

    <p>On the application/Web server</p> Signup and view all the answers

    Study Notes

    Types of Databases

    • Personal databases
    • Workgroup databases
    • Departmental/Divisional databases
    • Enterprise applications (transactional)
    • Data warehousing implementations

    Characteristics of Workgroup Databases

    • Each member of the workgroup has a computer
    • They are linked by means of a network
    • Each computer has a copy of the user interface application (client)
    • The database is on the server

    How Large are Typical Databases?

    • World Data Center for Climate: 220 terabytes of data
    • NERSC: 2.8 petabytes of data
    • AT&T: 323 terabytes of information
    • YouTube: 6 petabytes worth of extra information, 100 million videos watched per day, 65,000 videos added each day
    • Amazon: 59 million active customers, more than 42 terabytes of data

    What do we do with a Database?

    • Recording every single event that may take place in an organization
    • Contain the current operational data of the enterprise
    • Used in Enterprise Resource Planning (ERP) systems
    • Used in Data Warehousing implementations

    History of Databases

    • Databases now consist of a collection of records connected to one another through links (pointers)

    Relational Model

    • A relation is a named, two-dimensional table of data
    • A relation consists of rows (records-instances) and columns (attribute or field)
    • Requirements: unique name, atomic attribute values, unique rows, unique attribute names, irrelevant column and row order

    Relational Model in more details

    • Keys are special fields that serve two main purposes: primary keys and foreign keys
    • Keys can be simple (a single field) or composite (more than one field)
    • Keys are used as indexes to speed up the response to user queries

    Primary Keys

    • Are unique identifiers of the relation
    • Guarantee that all rows are unique
    • Examples include employee numbers, social security numbers, etc
    • Can be simple or Composite

    Foreign Keys

    • Referential Integrity constraint can be used with several rules that protect the integrity of data
    • Delete Rules: Restrict, Cascade, Set-to-Null

    Referential Integrity

    • A rule that states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null

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    Week_01_Chapter_01_and_04_Relational.pptx

    Description

    This quiz covers the characteristics of client-server model in database systems, including personal and workgroup databases. It discusses the advantages and drawbacks of this model, including the distribution of functionality between client computers and the server.

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