Cosmos DB overview and use cases in Azure - Mini Project: Build & Apply

Cosmos DB Overview and Use Cases

📖 Scenario: You are working as a cloud architect for a company that wants to store and access data globally with low latency. They want to understand how Azure Cosmos DB can help them achieve this goal.

🎯 Goal: Build a simple Azure Cosmos DB setup with a database and container, and configure it for global distribution to demonstrate its use cases.

📋 What You'll Learn

Create an Azure Cosmos DB account with Core (SQL) API

Create a database named RetailDB

Create a container named Products with partition key /category

Configure the Cosmos DB account for multi-region write to enable global distribution

💡 Why This Matters

🌍 Real World

Companies use Cosmos DB to build applications that need fast, global access to data, such as retail websites, gaming platforms, and IoT solutions.

💼 Career

Cloud architects and developers use Cosmos DB to design scalable, globally distributed databases that meet performance and availability requirements.

1

Create Cosmos DB account with Core (SQL) API

Create an Azure Cosmos DB account named myRetailAccount using the Core (SQL) API.

Azure

# Create Cosmos DB account named myRetailAccount with Core (SQL) API
# Your code here

Hint

Use the Azure CLI command az cosmosdb create with the --kind GlobalDocumentDB option for Core (SQL) API.

2

Create database RetailDB

Create a database named RetailDB in the Cosmos DB account myRetailAccount.

Azure

az cosmosdb create --name myRetailAccount --resource-group myResourceGroup --kind GlobalDocumentDB
# Create database RetailDB
# Your code here

Hint

Use az cosmosdb sql database create with the account name and database name.

3

Create container Products with partition key /category

Create a container named Products inside the database RetailDB with partition key /category.

Azure

az cosmosdb create --name myRetailAccount --resource-group myResourceGroup --kind GlobalDocumentDB
az cosmosdb sql database create --account-name myRetailAccount --resource-group myResourceGroup --name RetailDB
# Create container Products with partition key /category
# Your code here

Hint

Use az cosmosdb sql container create with the database name, container name, and partition key path.

4

Enable multi-region write for global distribution

Configure the Cosmos DB account myRetailAccount to enable multi-region write to allow global distribution.

Azure

az cosmosdb create --name myRetailAccount --resource-group myResourceGroup --kind GlobalDocumentDB
az cosmosdb sql database create --account-name myRetailAccount --resource-group myResourceGroup --name RetailDB
az cosmosdb sql container create --account-name myRetailAccount --resource-group myResourceGroup --database-name RetailDB --name Products --partition-key-path "/category"
# Enable multi-region write on myRetailAccount
# Your code here

Hint

Use az cosmosdb update with the --enable-multiple-write-locations true flag to enable multi-region writes.

Practice

1. What is the main benefit of using Azure Cosmos DB for global applications?

easy

A. It provides low latency and high availability worldwide.

B. It only supports SQL queries.

C. It requires manual scaling of resources.

D. It is designed for local, single-region apps only.

Solution

1. Step 1: Understand Cosmos DB's global distribution

   Cosmos DB is designed to replicate data across multiple regions to provide fast access and high availability.

2. Step 2: Identify the benefit for global apps

   This replication ensures low latency and continuous availability for users worldwide.

3. Final Answer:

   It provides low latency and high availability worldwide. -> Option A

4. Quick Check:

   Global apps need low latency and high availability = A [OK]

Hint: Global apps need fast, reliable data access worldwide [OK]

Common Mistakes:

• Thinking Cosmos DB only supports SQL
• Assuming manual scaling is required
• Believing it's for single-region use only

2. Which of the following is a supported API model in Azure Cosmos DB?

easy

A. Oracle SQL API

B. MySQL API

C. MongoDB API

D. PostgreSQL API

Solution

1. Step 1: Recall Cosmos DB supported APIs

   Azure Cosmos DB supports multiple APIs including SQL, MongoDB, Cassandra, Gremlin, and Table APIs.

2. Step 2: Identify the correct API from options

   MongoDB API is officially supported, while Oracle, MySQL, and PostgreSQL APIs are not.

3. Final Answer:

   MongoDB API -> Option C

4. Quick Check:

   MongoDB API is supported by Cosmos DB = B [OK]

Hint: Remember Cosmos DB supports MongoDB API, not Oracle or MySQL [OK]

Common Mistakes:

• Confusing Cosmos DB with relational databases
• Assuming all SQL-based APIs are supported
• Selecting unsupported database APIs

3. Given this Cosmos DB use case: A global e-commerce app needs to store product catalog data with fast reads and writes worldwide. Which Cosmos DB feature best supports this?

medium

A. Local SSD caching only

B. Multi-region replication with automatic failover

C. Single-region write with manual backups

D. Manual sharding without replication

Solution

1. Step 1: Analyze the requirement for global fast reads and writes

   The app needs data available quickly everywhere and must handle writes globally.

2. Step 2: Match Cosmos DB features to requirements

   Multi-region replication with automatic failover allows writes and reads in multiple regions with high availability and low latency.

3. Final Answer:

   Multi-region replication with automatic failover -> Option B

4. Quick Check:

   Global fast reads/writes need multi-region replication = C [OK]

Hint: Global writes need multi-region replication with failover [OK]

Common Mistakes:

• Choosing single-region write limits scalability
• Confusing caching with replication
• Ignoring automatic failover importance

4. You created a Cosmos DB container but notice your app experiences high latency when accessing data globally. What is the most likely cause?

medium

A. The container is configured with single-region write and no multi-region replication.

B. The container uses multi-region replication with automatic failover.

C. The container has indexing enabled for all properties.

D. The container is using the MongoDB API.

Solution

1. Step 1: Understand latency causes in global apps

   High latency often happens if data is only written and read from one region far from users.

2. Step 2: Identify configuration causing latency

   Single-region write without multi-region replication means users far from that region experience delays.

3. Final Answer:

   The container is configured with single-region write and no multi-region replication. -> Option A

4. Quick Check:

   Single-region write without replication causes high latency = A [OK]

Hint: Check if multi-region replication is enabled to reduce latency [OK]

Common Mistakes:

• Assuming indexing causes latency
• Confusing API choice with latency issues
• Believing multi-region replication increases latency

5. A company wants to build a globally distributed IoT app that collects sensor data continuously and requires automatic scaling and low latency. Which Cosmos DB feature combination best fits this use case?

hard

A. Gremlin API with no replication and fixed throughput

B. Single API support with manual scaling and single-region writes

C. Table API with single-region replication and manual failover

D. Multi-model support with multi-region writes and automatic scaling

Solution

1. Step 1: Identify IoT app requirements

   The app needs to handle continuous data ingestion globally with automatic scaling and low latency.

2. Step 2: Match Cosmos DB features to these needs

   Multi-model support allows flexible data types; multi-region writes enable global data ingestion; automatic scaling handles variable loads.

3. Final Answer:

   Multi-model support with multi-region writes and automatic scaling -> Option D

4. Quick Check:

   IoT needs global writes and scaling = D [OK]

Hint: IoT needs multi-region writes plus auto scaling [OK]

Common Mistakes:

• Choosing single-region writes limits global data ingestion
• Ignoring automatic scaling for variable IoT loads
• Selecting APIs without replication support