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SQL, Big Data and Distributed Systems

The DBMS, the data dictionary and distributed databases

  • 3 things to know
  • Component 2

Overview

Database management system, data dictionary and distributed system.

What you need to know

Answer each one before you reveal it.

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Key term

What does a database management system do?

Key term

What is a data dictionary, and what does it record?

Key term

What is a database management system?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a database management system?

    Model answer

    A database management system is the software that sits between the users and the stored data. The system handles the creation, retrieval, updating and security of that data.

  2. 2

    Give three functions performed by a database management system.

    Model answer

    A database management system maintains the structure of the database and enforces its integrity rules. The system also controls which users may reach each part of the data.

  3. 3

    Explain how a database management system provides data independence.

    Model answer

    The system separates the logical view a program uses from the way the data is physically stored. A change to the storage then needs no change to the program.

  4. 4

    What is a data dictionary?

    Model answer

    A data dictionary is the store of information about the data held in a database. The dictionary records the tables, the columns and the rules that apply to them.

  5. 5

    Name four things recorded in a data dictionary.

    Model answer

    A data dictionary records column names and their data types. A data dictionary also records field lengths and validation rules.

  6. 6

    Why is a data dictionary described as metadata?

    Model answer

    A data dictionary describes the structure of the data rather than holding the data itself. Metadata means data about data.

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