📖 What is Azure Cosmos DB?
Azure Cosmos DB is a globally distributed, multi-model database service. It supports document, graph, key-value, and column-family data models. It guarantees single-digit millisecond latency at the 99th percentile, with automatic and elastic scalability to handle demanding application workloads.
"Key exam focus: global distribution and multi-model capabilities. Understand the concept of Request Units (RUs) for throughput provisioning. Distractors often relate to traditional relational database limitations that Cosmos DB overcomes, such as scalability and geo-replication."
📚 Certification: Microsoft Azure Fundamentals (AZ-900)
🔑 What are the Key Concepts of Azure Cosmos DB?
- ▸ Cosmos DB offers multiple API options (SQL, MongoDB, Cassandra, Gremlin, Table) allowing developers to use familiar tools and skills.
- ▸ Globally distributed data ensures low latency for users worldwide through configurable replication and read regions.
- ▸ Request Units (RUs) measure throughput and are used to provision database resources; understanding RU/s is crucial for cost management.
- ▸ Automatic indexing speeds up queries without requiring manual index creation or maintenance, simplifying development.
- ▸ Multi-model support allows storing data in various formats within a single database, offering flexibility for diverse application needs.
🎯 How does Azure Cosmos DB appear on the AZ-900 Exam?
You may be asked to identify the Azure service best suited for an application requiring single-digit millisecond response times at a global scale, with automatic scaling.
A scenario might describe an application needing to store both relational and graph data; determine which Azure database service can handle both efficiently.
Expect questions about how to optimize Cosmos DB costs by adjusting Request Unit (RU) settings based on application workload patterns.
❓ Frequently Asked Questions
How does Cosmos DB handle data consistency?
Cosmos DB offers five well-defined consistency levels (Strong, Bounded Staleness, Session, Consistent Prefix, Eventual). Choosing the right level balances consistency needs with latency and availability requirements.
What are read regions and why are they important?
Read regions allow you to replicate your data to geographically closer locations, reducing read latency for users in those regions. This is key for global applications and improving user experience.
When would I choose Cosmos DB over Azure SQL Database?
Choose Cosmos DB when you need global distribution, multi-model support, and guaranteed low latency at scale. Azure SQL Database is better for applications requiring full ACID transactions and complex relational queries.