NoSQL Databases and Key/Value Stores Quiz

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Questions and Answers

What is the primary feature that distinguishes key/value stores from document stores?

Key/value stores store structured documents like JSON.

Key/value stores store data in a schema-less format.

Key/value stores consist of unstructured blobs. (correct)

Key/value stores allow transaction support.

Which type of NoSQL database maintains a schema-less blob for its values?

Key/value Stores (correct)

Columnar Family Stores

Graph Databases

Document Stores

What functionality does a document store have that a key/value store typically does not provide?

The support of multiple data formats without schema.

The capability to maintain complex relationships.

The ability to create indexes for faster search. (correct)

The ability to store data in memory only.

Which of the following is NOT a characteristic of key/value stores?

They use complex queries to access data. Signup and view all the answers

In what scenario might you use a key/value store?

To store customer preferences associated with login IDs. Signup and view all the answers

What is a primary characteristic of a NoSQL database?

Avoids the use of joins Signup and view all the answers

Which of the following best describes the data storage mechanism for NoSQL databases?

Data is stored in key/value pairs Signup and view all the answers

What does BASE stand for in the context of NoSQL transactions?

Basically available, Soft state, Eventual consistency Signup and view all the answers

In contrast to RDBMS, NoSQL databases are designed for which of the following?

Humongous data storage needs Signup and view all the answers

Which of the following is NOT a characteristic of RDBMS?

Uses a flexible schema Signup and view all the answers

Which of the following is a common NoSQL database?

MongoDB Signup and view all the answers

When referring to NoSQL, what does the term 'document root element' imply?

The main component in JSON or XML data storage Signup and view all the answers

Which of the following is a disadvantage of using an RDBMS compared to NoSQL databases?

Less flexibility in handling data structures Signup and view all the answers

What primary function do document stores serve in content management?

Content management of web pages Signup and view all the answers

In a document store, which of the following formats is typically used to express data?

XML or JSON Signup and view all the answers

What is the role of the default '_id' field in a MongoDB shard?

To serve as a primary index Signup and view all the answers

What is one reason why document stores can contain complex data that would otherwise require multiple relational tables?

They support hierarchical data structures. Signup and view all the answers

Which component in MongoDB helps in directing operations to the appropriate shard and returning results?

Query routers (mongos) Signup and view all the answers

Secondary indices in a document store can be defined on which of the following?

Single fields, multiple fields, and arrays Signup and view all the answers

Which of the following is an acceptable use of a document store?

Web analytics of stored log data Signup and view all the answers

What is a distinct advantage of using document-oriented databases over relational databases?

Document stores allow for more flexible data structuring and schema evolution. Signup and view all the answers

What happens to the consistency of a system when it prioritizes availability and partition tolerance according to the CAP theorem?

Consistency is sacrificed, leading to potential data discrepancies. Signup and view all the answers

Which property of a database system assures that a response is received for every request, even in the event of network failures?

Availability Signup and view all the answers

Under the CAP theorem, which two properties can a distributed database system achieve simultaneously?

Consistency and Availability Signup and view all the answers

What does the term 'partition tolerance' refer to in the context of the CAP theorem?

The system's continued operation during network failures. Signup and view all the answers

In a scenario where a database system guarantees consistency and requires network partitioning, what must happen to availability?

Availability is likely to be compromised. Signup and view all the answers

What process allows HBase to manage extremely large quantities of data?

Sharding Signup and view all the answers

Which of the following is an advantage of using HBase's columnar layout?

It can handle data in varying formats from row to row. Signup and view all the answers

How is a basic customer table with a column family created in HBase?

create 'customer', 'address' Signup and view all the answers

What command indiscriminately reads all contents of an HBase table?

scan 'customer' Signup and view all the answers

Which statement is true regarding retrieval of data from HBase tables?

The scan command is useful for reading all entries, but targeted queries are preferable for larger tables. Signup and view all the answers

What command is used to insert a new field for a customer in CouchDB?

put Signup and view all the answers

Which of the following statements accurately describes MongoDB?

It is a document database that is schema-free. Signup and view all the answers

In CouchDB, what is the primary structure used for storing data?

Documents Signup and view all the answers

What technology does CouchDB utilize for data interchange?

JavaScript Object Notation (JSON) Signup and view all the answers

What feature of CouchDB allows it to distribute and replicate data across server nodes?

Built-in replication Signup and view all the answers

Which of the following terms corresponds to a 'Field' in MongoDB?

Property Signup and view all the answers

Study Notes

NoSQL Database Overview

NoSQL databases are non-relational data management systems that do not require a fixed schema.
They are designed for handling large amounts of unstructured or semi-structured data.
NoSQL databases excel in scalability and performance in big data and real-time applications.
Examples of NoSQL databases include MongoDB, Cassandra, and HBase.

NoSQL Database Types

Key-Value Stores: Simple databases that consist of unique keys and values. Suitable for storing and retrieving data quickly, often use schema-less data formats.
Document Stores: Stores documents with self-describing characteristics (e.g., JSON, XML). Useful for flexible data where relationships are flexible.
Column-Family Stores: Organize data by column families. Useful for sparse datasets, potentially improving querying speed for associated rows in big datasets.
Graph Databases: Designed for relationships between data points: like social networks, relationships between people, etc. Graph databases can easily track these connections.

NoSQL Database Terminology

RDBMS: Partitions, Tables, Rows, Columns
NoSQL: Shard, Collection, Document, Aggregated, Attribute/field (JSON/XML)

RDBMS vs. NoSQL

Feature	RDBMS	NoSQL
Schema	Fixed	Flexible or schema-less
Scalability	Scaling up (expensive servers)	Scaling out (multiple, inexpensive servers)
Data structure	Rows and columns	Flexible, varies depending on the use type
ACID properties	Atomic, Consistent, Isolated, Durable	BASE (Basically Available, Soft state, Eventual consistency)
Query Methods	SQL (structured query language)	Often specific query languages/APIs

NoSQL Database Design

BASE Properties:
- Basically Available: The system is almost always available, even with network issues.
- Soft state: Data consistency in nodes may vary over time.
- Eventual consistency: Data will become correct over time, even across parts of a network or in disconnected nodes.
Logical Layers:
- Data Model Layer: With extensible formats (Map, Column Family, Document, Graph, and etc...).
- Data Distribution Layer: Ensures horizontal scaling across multiple servers.
- Persistence Layer: Data storage flexibility (disk, memory, or both).
- Interface Layer: Non-SQL Interfaces handle data access (REST, Thrift, and etc...).

Data Store Examples

Redis: Key-value store
Voldemort: Fast key-value store
CouchDB: Document store, based on JSON.
MongoDB: Document store, using JSON/BSON.
Cassandra: Column-family store
HBase: Column-family store, used with Hadoop/HDFS.
FlockDB: Graph database
Neo4j: Graph database

HBase

A NoSQL, column-family database built on Hadoop/HDFS.
Scalable, real-time, and provides random read/write access, essential in big data environments.
Organizes data by columns organized into column families, rather than rows, allowing fast access to certain attributes.
Uses a write-ahead log (WAL) for durability of data.
Partitions data into Regions automatically managed by the HRegionServer.
Uses a Master node (HMaster) to distribute and monitor.

CouchDB

A document-oriented NoSQL database.
Characterized by schema-free documents stored in JSON format,
Easy interface with REST-like method, allowing flexible data modification.
Distributed architecture with replication across servers.

MongoDB

Open-source, document-oriented database that uses JSON-like format,
Provides a solution to issues in traditional relational databases.
Scalable key-value database.

Cassandra

NoSQL, distributed database that supports horizontal scaling .
Handles large volumes of data.
Ideal for applications needing high availability and read/write scalability, like messaging systems.

CAP Theorem

Consistency (C): All nodes have the same data view.
Availability (A): The system continues to operate, even with node failures.
Partition Tolerance (P): The system will continue to function despite network partitions. In a distributed system, it is vital, as network failures are a frequent possibility.
No database is able to satisfy all three properties simultaneously. Developers must choose which two are essential for their demands.

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Description

Test your knowledge of NoSQL databases with this quiz that explores the distinctions between key/value stores and document stores. You'll also examine characteristics, advantages, and use cases of different types of databases. Perfect for anyone looking to deepen their understanding of modern data storage solutions.