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  1. LPU MCA Semester 1
  2. CAP570
  3. Unit 6

CAP570 · Unit 6: Advanced databases

Current trends in database technology and big data

10 practice questions · in the ETE syllabus

Practise this topicPractise this topic

Key points

  • Big data: volume, velocity, variety, plus veracity and value
  • Structured, semi-structured and unstructured data
  • Hadoop uses HDFS storage and MapReduce processing
  • Trends: NoSQL, NewSQL, cloud and in-memory databases

Big data is data too large, fast or varied for traditional tools. Its classic characteristics are the three Vs: volume (amount), velocity (speed of generation and processing) and variety (many formats). Veracity (trustworthiness of data) and value are often added.

Kind of dataExamples
StructuredRows and columns in relational tables
Semi-structuredJSON, XML (tags or keys, flexible schema)
UnstructuredPhotos, audio, video, free text

A single server can only scale up so far, so big data is spread over clusters of ordinary machines. Hadoop stores data in HDFS and processes it with MapReduce: the map step emits (key, value) pairs, such as (word, 1), and the reduce step combines values per key, for example summing counts for a word count.

Current database trends include NoSQL and NewSQL systems, cloud databases (database as a service), in-memory databases that keep data in RAM for speed, graph databases for relationships, and data lakes that store raw data of every kind.

Exam trap: velocity is about speed, volume about size, variety about formats and veracity about trust. Mixing formats shows variety, not volume.

Try two questions

Question 1 · Tier 3, Apply

A company stores customer tables, social media posts and CCTV video together. Which big data characteristic does this mixture of formats illustrate?

  1. Volume
  2. Velocity
  3. Veracity
  4. Variety
Show the answer

D. Variety means data arrives in many formats at once.

Why not A: Volume is about the amount of data.

Why not B: Velocity is about the speed of arrival.

Why not C: Veracity is about the trustworthiness of the data.

Question 2 · Tier 2, Understand

Photos, audio recordings and videos are usually classified as

  1. Structured data
  2. Semi-structured data
  3. Unstructured data
  4. Relational data
Show the answer

C. Unstructured data has no predefined data model.

Why not A: Structured data fits rows and columns.

Why not B: Semi-structured data has tags or keys.

Why not D: Relational data is stored in tables.