Creating Tables with Provisioned and On-Demand Capacity Modes in DynamoDB

4.2.1 Creating Tables with Provisioned and On-Demand Capacity Modes

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. One of the key features of DynamoDB is its flexible capacity modes, which allow you to optimize costs and performance based on your application’s workload patterns. In this section, we will delve into the details of creating tables with both provisioned and on-demand capacity modes, providing comprehensive guidance for Java and Clojure developers.

Understanding Capacity Modes in DynamoDB

Before diving into the technical details, it’s crucial to understand the fundamental differences between provisioned throughput and on-demand capacity modes.

Provisioned Throughput Mode

Provisioned throughput mode allows you to specify the number of read and write capacity units required for your application. This mode is ideal for applications with predictable traffic patterns, where you can anticipate the workload and allocate resources accordingly. The key characteristics of provisioned throughput mode include:

• Cost Efficiency: By allocating a fixed number of capacity units, you can optimize costs for predictable workloads.
• Predictability: Ensures consistent performance by reserving the necessary resources.
• Auto Scaling: You can enable auto-scaling to automatically adjust capacity based on traffic patterns.

On-Demand Capacity Mode

On-demand capacity mode, on the other hand, is designed for applications with unpredictable or variable traffic patterns. This mode automatically scales to accommodate the workload, eliminating the need for manual capacity planning. Key features of on-demand capacity mode include:

• Flexibility: Automatically scales to handle any level of request traffic.
• Simplicity: No need to specify capacity units, making it easy to manage.
• Cost: You pay for the actual read and write requests, which can be more cost-effective for sporadic workloads.

Creating a DynamoDB Table via AWS Console

Let’s start by creating a DynamoDB table using the AWS Management Console. Follow these steps:

1. Sign in to the AWS Management Console and open the DynamoDB console at https://console.aws.amazon.com/dynamodb.

2. Click on “Create Table.” This will open the table creation wizard.

3. Enter the Table Name and Primary Key. For example, you might create a table named Orders with a primary key OrderId of type String.

4. Select Capacity Mode:

   • Choose Provisioned if you have predictable traffic and want to specify read and write capacity units.
   • Choose On-Demand if your traffic is unpredictable or you prefer automatic scaling.

5. Configure Additional Settings:

   • For provisioned mode, specify the read and write capacity units.
   • Optionally, enable auto-scaling for provisioned mode.
   • Configure additional settings such as encryption, tags, and global secondary indexes if needed.

6. Review and Create:

   • Review your settings and click Create to create the table.

Creating a DynamoDB Table via AWS CLI

For developers who prefer command-line interfaces, the AWS CLI provides a powerful way to create DynamoDB tables. Here’s how you can do it:

1. Open your terminal and ensure that the AWS CLI is installed and configured with your credentials.

2. Create a Table with Provisioned Capacity:

   aws dynamodb create-table \
       --table-name Orders \
       --attribute-definitions AttributeName=OrderId,AttributeType=S \
       --key-schema AttributeName=OrderId,KeyType=HASH \
       --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5
   

3. Create a Table with On-Demand Capacity:

   aws dynamodb create-table \
       --table-name Orders \
       --attribute-definitions AttributeName=OrderId,AttributeType=S \
       --key-schema AttributeName=OrderId,KeyType=HASH \
       --billing-mode PAY_PER_REQUEST
   

Best Practices for Selecting Capacity Modes

Choosing the right capacity mode is crucial for optimizing both performance and cost. Here are some best practices to consider:

• Analyze Traffic Patterns: Use historical data to understand your application’s traffic patterns. If your workload is predictable, provisioned mode with auto-scaling might be more cost-effective.

• Start with On-Demand: For new applications or those with unpredictable workloads, start with on-demand mode. This allows you to gather data on traffic patterns without the risk of under-provisioning.

• Monitor and Adjust: Regularly monitor your application’s performance and costs. Use AWS CloudWatch to track metrics and adjust capacity modes as needed.

• Consider Auto Scaling: If you choose provisioned mode, enable auto-scaling to automatically adjust capacity based on demand, reducing the risk of throttling.

Switching Between Capacity Modes

There may be scenarios where you need to switch between capacity modes. For example, an application that starts with on-demand mode might switch to provisioned mode as traffic stabilizes. Here’s how you can switch modes:

1. Open the DynamoDB Console and navigate to the table you want to modify.

2. Select the “Capacity” tab and click on “Manage Capacity.”

3. Switch Capacity Mode:

   • To switch to provisioned mode, specify the desired read and write capacity units.
   • To switch to on-demand mode, select the “On-Demand” option.

4. Save Changes to apply the new capacity mode.

Conclusion

Creating DynamoDB tables with the appropriate capacity mode is a critical step in designing scalable and cost-effective data solutions. By understanding the differences between provisioned and on-demand capacity modes, and following best practices for selecting and switching modes, you can optimize your application’s performance and costs.

In the next section, we will explore how to access DynamoDB from Clojure using the Amazonica library, enabling seamless integration with your Clojure applications.

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