2 Data Structures, Types, and Formats

Question 1

What is the main focus of this chapter?

Answer 1

Data storage and the various formats of data.

Question 2

What are the two main categories of databases?

Answer 2

• Structured
• Unstructured

Question 3

What defines a structured database?

Answer 3

It follows a standardized format with a clear and logical structure.

Question 4

What are the two main archetypes of structured databases?

Answer 4

• Defined rows/columns
• Key-value pairs

Question 5

How are defined rows and columns organized?

Answer 5

In tables or spreadsheets where columns represent variables and rows represent data points.

Question 6

What do key-value pairs represent in a structured database?

Answer 6

Data objects where each object has the same set of keys with different values.

Question 7

What characterizes unstructured data?

Answer 7

It has no attempt at organization and is often stored as individual files.

Question 8

What are the two groups of unstructured data?

Answer 8

• Undefined fields
• Machine data

Question 9

What types of file formats are included in undefined fields?

Answer 9

• Text files
• Audio files
• Video files
• Images
• Social media data
• Emails

Question 10

What is machine data?

Answer 10

Data automatically generated by software without human intervention.

Question 11

What is the difference between relational and non-relational databases?

Answer 11

Relational databases store information and relationships, while non-relational databases store information only.

Question 12

What language is primarily used for querying relational databases?

Answer 12

Structured Query Language (SQL)

Question 13

True or False: All SQL databases are structured and relational.

Answer 13

True

Question 14

True or False: All non-relational databases are unstructured.

Answer 14

True

Question 15

What are the two most basic types of data schemas covered in this chapter?

Answer 15

• Star schema
• Snowflake schema

Question 16

What is the structure of a star schema?

Answer 16

A central key table with dimension tables connected directly to it.

Question 17

What are the pros of a star schema?

Answer 17

• Simple
• Fewer joins required
• Easier to understand

Question 18

What are the cons of a star schema?

Answer 18

• High redundancy
• Denormalized

Question 19

What distinguishes a snowflake schema from a star schema?

Answer 19

It has two levels of dimension tables instead of one.

Question 20

What are the pros of a snowflake schema?

Answer 20

• Low redundancy
• Normalized

Question 21

What are the cons of a snowflake schema?

Answer 21

• More complicated
• More joins required

Question 22

What is a data warehouse?

Answer 22

A database used for structured relational tables, holding large amounts of processed transactional data.

Question 23

What is a data mart?

Answer 23

A specialized subset of a data warehouse holding processed information on a specific topic.

Question 24

What is a data lake?

Answer 24

A storage system for large amounts of raw, unprocessed data, which can be structured, unstructured, or a combination.

Question 25

Fill in the blank: A data mart is designed to be _______ enough for analysts or customer support employees to access by themselves.

Answer 25

[self-service]

Question 26

What is a data mart?

Answer 26

A data mart is a subset of a data warehouse that contains customer-facing data and is designed for self-service access by analysts or customer support employees ## Footnote Data marts prioritize ease of use and often follow a star schema.

Question 27

What is a data lake?

Answer 27

A data lake stores large amounts of raw, unprocessed data, which can include structured, unstructured, or a combination of both types ## Footnote Data lakes are often used by data scientists and do not follow any specific schema.

Question 28

Who typically creates data warehouses and data lakes?

Answer 28

Data warehouses and data lakes are usually created by specialized data engineers, and many companies only have one ## Footnote They are often created through third-party services or software.

Question 29

What are some popular data warehouse tools?

Answer 29

* Snowflake * Hevo * Amazon Web Services (AWS) data warehouse tools * Microsoft Azure data warehouse tools * Google data warehouse tools

Question 30

What are the two options for updating a current value in a dataset?

Answer 30

* Overwrite historical values * Keep historical values

Question 31

What is the benefit of overwriting historical values?

Answer 31

It keeps your dataset smaller and simpler, but historical data is lost ## Footnote Historical data is required for trend analysis.

Question 32

What columns are added to keep historical values?

Answer 32

* Active Record * Active Start * Active End

Question 33

What does the Active Record column indicate?

Answer 33

It indicates whether the specified value is the most current value, marked as Yes or No.

Question 34

What are the consequences of changing the number of variables being recorded?

Answer 34

It creates null values in the dataset ## Footnote Null values occur whether you are adding new columns or removing existing ones.

Question 35

What are the four common data types that everyone working with data should know?

Answer 35

* Date * Numeric * Alphanumeric * Currency

Question 36

How should dates be formatted according to ISO recommendations?

Answer 36

* YYYY-MM-DD * YYYY-MM-DD HH:MI:SS

Question 37

What is numeric data?

Answer 37

Numeric data is made up of numbers, which can be whole numbers or decimals.

Question 38

What does alphanumeric data include?

Answer 38

Alphanumeric data includes numbers and letters, except for values in scientific notation.

Question 39

What is currency data?

Answer 39

Currency data includes monetary values, typically denoted with a currency symbol.

Question 40

What are the two types of numeric data?

Answer 40

* Discrete * Continuous

Question 41

What defines discrete variables?

Answer 41

Discrete variables are counts that usually describe whole numbers or integers.

Question 42

What are continuous variables?

Answer 42

Continuous variables can represent an infinite number of values between two points and are often measured as decimals.

Question 43

What are the three main types of categorical variables?

Answer 43

* Binary * Nominal * Ordinal

Question 44

What distinguishes independent variables from dependent variables?

Answer 44

Independent variables are manipulated directly, while dependent variables are measured and depend on independent variables.

Question 45

What file types are commonly encountered by data analysts?

Answer 45

* Text (TXT) * Image (JPEG) * Audio (MP3) * Video (MP4) * Flat (CSV) * Website (HTML)

Question 46

What are flat files?

Answer 46

Flat files contain a simple two-dimensional dataset or spreadsheet, such as TSV or CSV.

Question 47

What is the difference between TSV and CSV?

Answer 47

TSV values are separated by tabs, while CSV values are separated by commas.

Question 48

What are the common image file types?

Answer 48

* JPG/JPEG * PNG * GIF * BMP * RAW

Question 49

What formats do audio files commonly use?

Answer 49

* MP3 * WAV * WMA * AAC * ALAC

Question 50

What are some popular video file formats?

Answer 50

* MP4 * WMV * MOV * FLV * AVI

Question 51

What are the website file types recognized by the exam?

Answer 51

* HTML * XML * JSON

Question 52

What is the purpose of HTML?

Answer 52

HTML is used to structure websites and store information between tags.

Question 53

What distinguishes XML from HTML?

Answer 53

XML tags have no pre-determined meanings and can be customized, while HTML tags have specific meanings.

Question 54

What is HTML primarily used for?

Answer 54

Website structure and occasionally passing information

Question 55

How is information stored in HTML?

Answer 55

Between tags that create elements with specific meanings

Question 56

What is XML similar to?

Answer 56

HTML

Question 57

In XML, what is unique about the tags?

Answer 57

They have no pre-determined meanings

Question 58

What is a key feature of JSON?

Answer 58

Specializes in storing and passing information

Question 59

How does a JSON file structure data?

Answer 59

Contains a list of data objects using key-value pairs

Question 60

What is the main difference between JSON and HTML/XML?

Answer 60

JSON does not contribute to website structure

Question 61

What types of databases were covered in this chapter?

Answer 61

Structured and unstructured databases

Question 62

What are the two types of databases discussed?

Answer 62

Relational and non-relational databases

Question 63

What types of schemas were mentioned?

Answer 63

Star and snowflake schemas

Question 64

What are the three types of data storage mentioned?

Answer 64

Data warehouses, data marts, and data lakes

Question 65

What is a characteristic of a data lake?

Answer 65

Focuses on raw, unprocessed data

Question 66

True or False: JSON can have pre-determined tag meanings like XML.

Answer 66

False

Question 67

Fill in the blank: A smart thermometer sends data to a ______.

Answer 67

local database

Question 68

What type of schema is most appropriate for non-technical client-facing agents?

Answer 68

Star schema

Question 69

What will historic values be for a newly added column in a dataset?

Answer 69

Null

Question 70

What type of data does a file with the '.png' extension contain?

Answer 70

Image