> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> This article provides an overview of Azure Cosmos DB, highlighting its global distribution, multi-model APIs, and key features for data management.

Welcome to **Azure Data Fundamentals** Module 4. In this lesson, we’ll dive into **Azure Cosmos DB**, Microsoft’s globally distributed, multi-model database service. Cosmos DB delivers turnkey global distribution, elastic scalability, and comprehensive SLAs for throughput, availability, latency, and consistency.

## Key Features of Azure Cosmos DB

Azure Cosmos DB extends the familiar semi-structured model of Azure Table Storage and adds two powerful capabilities:

1. **Global Distribution**
2. **Multi-Model APIs**

### Global Distribution Overview

Cosmos DB’s global distribution lets you transparently replicate your data to any number of Azure regions. This ensures:

* High availability with 99.999% read/write SLA
* Millisecond latency for reads and writes
* Built-in disaster recovery and failover

<Frame>
  ![The image is an illustration explaining Cosmos DB, a semi-structured database that can distribute data to multiple regions, with a world map showing various locations.](https://kodekloud.com/kk-media/image/upload/v1752872937/notes-assets/images/DP-900-Microsoft-Azure-Data-Fundamentals-Introduction/cosmos-db-semi-structured-database-map.jpg)
</Frame>

In Azure, a **region** consists of one or more data centers with virtually zero network latency between them. By replicating your containers and databases across regions, Cosmos DB automatically routes requests to the nearest replica.

<Callout icon="lightbulb" color="#1CB2FE">
  Global distribution not only reduces latency but also improves resilience by automatically failing over to another region if one goes offline.
</Callout>

### Multi-Model API Support

Cosmos DB lets you choose the API that best fits your workload or existing codebase. Each API provides a well-documented surface area for data operations, so your application doesn’t need to know about the service internals.

<Frame>
  ![The image is a diagram illustrating the concept of APIs (Application Programming Interfaces), showing two applications connected by dotted lines, with a label indicating "Application Programming Interface."](https://kodekloud.com/kk-media/image/upload/v1752872938/notes-assets/images/DP-900-Microsoft-Azure-Data-Fundamentals-Introduction/api-diagram-applications-interfaces.jpg)
</Frame>

#### Supported Cosmos DB APIs

| API Model      | Description                                         | Query Language / Surface        |
| -------------- | --------------------------------------------------- | ------------------------------- |
| Document API   | JSON-based documents                                | Core (SQL) API & MongoDB native |
| Table API      | Key-value store compatible with Azure Table Storage | OData / Azure Storage SDK       |
| Gremlin API    | Property graph with vertices and edges              | Gremlin                         |
| Cassandra API  | Wide-column store with tunable consistency          | Cassandra Query Language (CQL)  |
| PostgreSQL API | Relational model for Postgres workloads             | PostgreSQL wire protocol        |

<Frame>
  ![The image illustrates the integration of Cosmos DB with various database types, including documents, key-value tables, relational databases, graphs, and column-family stores, featuring technologies like MongoDB, NoSQL, Table Storage, PostgreSQL, Gremlin, and Cassandra.](https://kodekloud.com/kk-media/image/upload/v1752872940/notes-assets/images/DP-900-Microsoft-Azure-Data-Fundamentals-Introduction/cosmos-db-integration-database-types.jpg)
</Frame>

## Global Data Access Example

To see global distribution in action, imagine a manufacturing plant in Mumbai and a customer portal in Apollo. By configuring Cosmos DB to replicate between **South India** and **Central India** regions, both employees and clients experience low-latency reads and writes:

<Frame>
  ![The image shows a world map with icons representing data distribution locations, illustrating global data sharing with Cosmos DB for low latency access.](https://kodekloud.com/kk-media/image/upload/v1752872942/notes-assets/images/DP-900-Microsoft-Azure-Data-Fundamentals-Introduction/world-map-data-distribution-cosmos-db.jpg)
</Frame>

**Workflow**

1. A sensor in Mumbai writes telemetry to the nearest Cosmos DB endpoint.
2. Cosmos replicates the data to Apollo in under 10 ms.
3. A customer dashboard in Apollo reads the latest data from the local replica.

<Callout icon="triangle-alert" color="#FF6B6B">
  Be mindful of your chosen consistency level (e.g., Session, Consistent Prefix) to balance latency and data correctness across regions.
</Callout>

## Links and References

* [Azure Cosmos DB Documentation](https://docs.microsoft.com/azure/cosmos-db/)
* [Azure Data Fundamentals (DP-900)](https://learn.microsoft.com/learn/paths/examine-fundamentals-of-azure/?WT.mc_id=dp-900)
* [Consistency Levels in Azure Cosmos DB](https://docs.microsoft.com/azure/cosmos-db/consistency-levels)

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