Computer Science
Grade 10
20 min
NoSQL Databases
NoSQL Databases
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1
Introduction & Learning Objectives
Learning Objectives
Define what a NoSQL database is and how it differs from a traditional SQL (relational) database.
Identify the four main types of NoSQL databases: Document, Key-Value, Column-Family, and Graph.
Explain the concept of a flexible schema and its advantages.
Describe the concept of horizontal scaling and why it's important for modern applications.
Analyze a simple application requirement and suggest an appropriate NoSQL database type.
Model a simple data entity, like a user profile, using JSON format for a document database.
Ever wonder how social media apps handle millions of posts, likes, and photos every second without crashing? 🤔 It's not magic, it's a different way of thinking about data!
In this lesson, we'll explore the world of No...
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Key Concepts & Vocabulary
TermDefinitionExample
NoSQL DatabaseA type of database that does not use the traditional table-based relational model of SQL. It provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases.Instead of a neat table of users with columns for 'ID', 'Name', and 'Email', a NoSQL database might store each user's information in a flexible document, like a digital file folder.
SchemaThe blueprint or structure of a database. In SQL, the schema is rigid and defined upfront (e.g., a 'users' table must have 'id', 'name', 'email' columns). In most NoSQL databases, the schema is flexible or non-existent.In a NoSQL document database, one user profile...
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Core Syntax & Patterns
JSON Data Structure
{ "key": "value", "numberKey": 123, "arrayKey": ["item1", "item2"] }
Many NoSQL databases, especially Document databases, use JSON (JavaScript Object Notation) to structure data. Data is stored in key-value pairs. Keys are strings in double quotes, and values can be strings, numbers, booleans, arrays, or even other JSON objects.
BASE vs. ACID Principle
BASE: Basically Available, Soft state, Eventually consistent.
While SQL databases follow ACID (Atomicity, Consistency, Isolation, Durability) for reliability, many NoSQL databases follow BASE. This model prioritizes availability over strict consistency, meaning the database is always responsive, but data across different servers might be temporaril...
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Challenging
You are designing a video streaming platform's user profile page. It needs to store user details (name, email), a list of their favorite video IDs, and their viewing history (video ID, timestamp). The number of favorite videos and history entries will grow over time. Which NoSQL approach is best and why?
A.Document database, using a single JSON document per user. This allows the 'favorites' and 'history' arrays to grow easily within a flexible structure.
B.Graph database to model the relationship between the user and every video they've watched. This is best for relationships.
C.Key-Value store with the user ID as the key and all other data as a single, massive text string. This is simplest.
D.separate Document for the user, another for favorites, and a third for history, to keep them isolated.
Challenging
A startup is building a new application. The development team is small and the application requirements are expected to change frequently. They need to launch quickly. However, the app will handle financial transactions later. Why might they choose a Document-based NoSQL database *initially*, even though an SQL database is better for transactions?
A.Because NoSQL databases are less secure and easier to hack into, which is fine for a startup.
B.The flexible schema of a Document DB allows for rapid development and easy adaptation to changing requirements, which is a higher priority than transactional integrity at the very beginning.
C.Because NoSQL databases are always cheaper and require no expert knowledge to manage.
D.The only reason would be that the developers don't know SQL.
Challenging
An online multiplayer game needs to store player state (position, health, inventory) that is updated several times per second. It also needs to store a temporary list of players currently in a specific game lobby. Which combination of NoSQL databases would be most effective for these two distinct needs?
A.Use a Graph database for both, to model player interactions.
B.Use a Document database for player state and a Graph database for the lobby list.
C.Use a traditional SQL database for both to ensure data is never lost.
D.Use a Key-Value store for the fast-updating player state (keyed by playerID) and also for the temporary lobby list (keyed by lobbyID).
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