NoSQL database types (document, key-value, column, graph) in HLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the NoSQL database type that stores data as JSON-like documents.

HLD

The [1] database stores data in flexible, JSON-like documents.

Drag options to blanks, or click blank then click option'

Acolumn

Bdocument

Ckey-value

Dgraph

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing document database with key-value database.

Thinking column databases store JSON documents.

The document database stores data as JSON-like documents, allowing flexible and nested data structures.

2fill in blank

medium

Complete the code to identify the NoSQL database type that stores data as simple key and value pairs.

HLD

A [1] database stores data as pairs of keys and their associated values.

Drag options to blanks, or click blank then click option'

Akey-value

Bcolumn

Cdocument

Dgraph

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing key-value with document databases.

Thinking column databases use key-value pairs.

Key-value databases store data as simple pairs, where each key maps directly to a value.

3fill in blank

hard

Fix the error in the statement about the NoSQL database type that organizes data in tables with rows and columns.

HLD

The [1] database type stores data in tables with rows and columns, similar to relational databases.

Drag options to blanks, or click blank then click option'

Agraph

Bdocument

Ccolumn

Dkey-value

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing column databases with relational databases.

Thinking key-value databases use tables.

Column databases store data in tables but organize data by columns, allowing efficient queries on large datasets.

4fill in blank

hard

Fill both blanks to complete the description of the NoSQL database type that models data as nodes and edges.

HLD

A [1] database models data as [2] and edges to represent relationships.

Drag options to blanks, or click blank then click option'

Agraph

Bdocuments

Cnodes

Dkey-value

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing graph with document or key-value databases.

Confusing nodes with documents.

Graph databases use nodes and edges to represent entities and their relationships, ideal for connected data.

5fill in blank

hard

Fill all three blanks to complete the example of a NoSQL database type, its data structure, and a use case.

HLD

The [1] database stores data as [2] and is often used for [3] analysis.

Drag options to blanks, or click blank then click option'

Agraph

Bnodes and edges

Csocial network

Dkey-value

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing key-value instead of graph for social network use.

Confusing data structure with document format.

Graph databases store data as nodes and edges and are commonly used for social network analysis to explore relationships.

Practice

1. Which NoSQL database type stores data as flexible JSON-like documents, allowing nested structures?

easy

A. Document database

B. Key-value database

C. Column database

D. Graph database

Solution

1. Step 1: Understand document database structure

   Document databases store data in JSON-like documents that can have nested fields and arrays.

2. Step 2: Compare with other NoSQL types

   Key-value stores use simple key and value pairs, column stores organize data by columns, and graph databases focus on relationships.

3. Final Answer:

   Document database -> Option A

4. Quick Check:

   Nested JSON-like data = Document database [OK]

Hint: Documents = JSON-like nested data [OK]

Common Mistakes:

• Confusing key-value stores with document stores
• Thinking column stores store JSON documents
• Mixing graph databases with document databases

2. Which of the following is the correct way to describe a key-value store?

easy

A. Stores data as interconnected nodes and edges

B. Stores data in tables with rows and columns

C. Stores data as simple pairs of keys and values

D. Stores data as nested JSON documents

Solution

1. Step 1: Define key-value store

   Key-value stores save data as pairs: a unique key and its associated value, like a dictionary.

2. Step 2: Eliminate other options

   Graphs use nodes and edges, column stores use tables with columns, and document stores use nested JSON.

3. Final Answer:

   Stores data as simple pairs of keys and values -> Option C

4. Quick Check:

   Key-value = key and value pairs [OK]

Hint: Key-value = simple pairs [OK]

Common Mistakes:

• Confusing graph databases with key-value stores
• Thinking key-value stores use tables
• Mixing document stores with key-value stores

3. Given a graph database storing people and their friendships, which query result would you expect from a query asking for all friends of 'Alice'?

medium

A. A list of key-value pairs with friend names

B. A set of nodes connected to 'Alice' by edges labeled 'friend'

C. A table with columns for friend names and ages

D. A JSON document with nested friend details

Solution

1. Step 1: Understand graph database query output

   Graph queries return nodes and edges; friends of 'Alice' are nodes connected by 'friend' edges.

2. Step 2: Compare with other data formats

   Key-value pairs, tables, and JSON documents are typical of other NoSQL types, not graph databases.

3. Final Answer:

   A set of nodes connected to 'Alice' by edges labeled 'friend' -> Option B

4. Quick Check:

   Graph query = nodes and edges [OK]

Hint: Graph = nodes connected by edges [OK]

Common Mistakes:

• Expecting JSON documents from graph queries
• Thinking graph data is tabular
• Confusing key-value pairs with graph edges

4. You wrote a query to retrieve data from a column store but got an error. Which mistake likely caused this?

medium

A. Used SQL SELECT syntax without specifying columns

B. Used key-value pairs instead of column names

C. Tried to traverse edges like in a graph database

D. Tried to query nested JSON documents directly

Solution

1. Step 1: Understand column store query requirements

   Column stores require specifying columns in queries; missing columns causes errors.

2. Step 2: Analyze other options

   Nested JSON is for document stores, key-value pairs are for key-value stores, and edge traversal is for graph databases.

3. Final Answer:

   Used SQL SELECT syntax without specifying columns -> Option A

4. Quick Check:

   Column store queries need columns specified [OK]

Hint: Specify columns in column store queries [OK]

Common Mistakes:

• Using document store syntax on column stores
• Trying graph traversal in column stores
• Confusing key-value pairs with columns

5. You need to design a social network app that quickly finds mutual friends between users. Which NoSQL database type is best suited and why?

hard

A. Column database, because it stores data in columns

B. Key-value store, because it is the fastest for any query

C. Document database, because it stores nested user data

D. Graph database, because it efficiently handles relationships

Solution

1. Step 1: Identify the data need for mutual friends

   Finding mutual friends requires exploring relationships between users efficiently.

2. Step 2: Match data need to NoSQL type

   Graph databases specialize in storing and querying relationships like friendships quickly.

3. Step 3: Evaluate other options

   Document stores handle nested data but not relationship queries efficiently; key-value stores are simple but not optimized for relationships; column stores focus on columnar data.

4. Final Answer:

   Graph database, because it efficiently handles relationships -> Option D

5. Quick Check:

   Relationship queries = Graph database [OK]

Hint: Use graph DB for relationship-heavy apps [OK]

Common Mistakes:

• Choosing document DB for relationship queries
• Assuming key-value stores handle complex queries
• Confusing column stores with relationship handling