12 NoSQL Overview and Key-Value Stores

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

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

Balanced Availability, Strong State, Eventual Consensus

Basic Availability, Soft State, Eventually Stable

Broadly Available, Static State, Increased Consistency

Basically Available, Soft State, Eventual Consistency (correct)

In NoSQL databases, what is generally lacked compared to traditional databases?

Scalability

ACID transactions (correct)

High performance

Data organization

Which of the following can best describe the update process in a BASE system?

Consistency is guaranteed at all times.

Updates happen through a series of strict transactions.

The system may change state over time without external input. (correct)

Always immediate consistency across all nodes.

What type of data model is primarily used in key-value stores?

Hash table Signup and view all the answers

Which characteristic of key-value stores contributes to their ability to provide high performance?

O(1) reading and writing capabilities Signup and view all the answers

What is the main advantage of using a key-value store over more complex database systems?

Simpler data models and high performance Signup and view all the answers

Why are joins typically performed in the application code when using NoSQL databases?

NoSQL stores generally do not support joins natively. Signup and view all the answers

What is the function of a graph database within the NoSQL category?

To represent data as vertices and edges. Signup and view all the answers

What is the main focus of a document store?

Storing documents such as XML, JSON, or binary Signup and view all the answers

Which of the following statements about document stores is true?

Document stores allow querying based on the internal structure of the document. Signup and view all the answers

What differentiates a wide column store from other storage types?

The basic unit of data is a column name/value pair. Signup and view all the answers

Which system is acknowledged as the first wide column store?

Bigtable Signup and view all the answers

What feature distinguishes key-value stores from document stores?

Key-value stores do not support complex queries. Signup and view all the answers

Which of the following is a characteristic of document stores?

Documents can be organized into collections or directories. Signup and view all the answers

Why might a developer choose a document store for data storage?

To utilize high flexibility for occasionally changing data. Signup and view all the answers

What is the primary purpose of timestamps in wide column stores?

For versioning and conflict resolution Signup and view all the answers

What is a primary characteristic of wide column stores like BigTable and Cassandra?

Keys are maintained in lexicographic order. Signup and view all the answers

Which data structure is used to represent records and relationships in a graph database?

Nodes and arcs Signup and view all the answers

What is a significant advantage of using NoSQL databases?

They can handle semi-structured and non-relational data. Signup and view all the answers

What type of data is particularly well-suited for NoSQL databases?

Rapidly ingested log and clickstream data. Signup and view all the answers

Which of the following is a limitation of graph databases?

They may lack widely available development tools. Signup and view all the answers

Why might developers prefer SQL databases over NoSQL in certain situations?

SQL databases provide fast lookups by index. Signup and view all the answers

What type of relationships do graph databases excel at managing?

Complex relationships with many foreign keys. Signup and view all the answers

What is a primary design consideration that may lead to choosing NoSQL over SQL?

Storage of many TB or PB of data. Signup and view all the answers

Study Notes

NoSQL Overview

NoSQL is a collection of data types including key-value, document, wide column, or graph databases
Data is denormalized, and joins are usually in application code
NoSQL stores generally lack true ACID transactions, favoring eventual consistency
BASE is often used to describe NoSQL properties, choosing availability over consistency
- Availability: system guarantees availability
- Soft state: system state can change over time
- Eventual consistency: system becomes consistent when no inputs are received
Understanding NoSQL type best fits use case crucial
- Next sections review key-value, document, wide column, and graph databases

Key-Value Store

Abstraction: hash table
Commonly uses memory or SSD, maintaining keys in lexicographic order
Enables O(1) reads and writes
Allows efficient key range retrievals
Suitable for metadata storage with values
Offers high performance for simple data models or rapidly changing data
Application layer handles additional complexity due to limited operations

Document Store

Abstraction: key-value store with documents as values
Primarily uses XML, JSON, or binary documents
Provides APIs or query languages to query documents based on internal structure
Can organize documents by collections, tags, metadata, or directories, allowing flexibility
Some stores (e.g., MongoDB, CouchDB) offer SQL-like languages
DynamoDB supports key-value and documents
Suitable for occasionally changing data due to high flexibility

Wide Column Store

Abstraction: nested map
Basic data unit is a column (name/value pair) grouped into column families
Column families can be further grouped (super column families)
Allows independent access to columns within a row key
Each value includes a timestamp for versioning and conflict resolution
Popular choices include Google Bigtable, HBase, and Cassandra (key maintained in lexicographic order)
Offers high availability and scalability, good for very large datasets

Graph Database

Each node represents a record, and arcs represent relationships between nodes
Optimized for complex relationships (many foreign keys or many-to-many)
Suitable for data models like social networks
Relatively new, with limited tools and resources
Often accessed via REST APIs

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the fundamentals of NoSQL databases, focusing on key-value stores. It explores the characteristics, benefits, and use cases of different NoSQL data types and emphasizes the importance of understanding each type's fit for specific applications.