Скачать или смотреть Creating a Global Secondary Index in DynamoDB with a Composite Sort Key

Learn how to create a `Global Secondary Index` in DynamoDB using a `composite sort key`, allowing for flexible access patterns in your application.
---
This video is based on the question https://stackoverflow.com/q/72863999/ asked by the user 'Quang' ( https://stackoverflow.com/u/13786545/ ) and on the answer https://stackoverflow.com/a/72864182/ provided by the user 'hunterhacker' ( https://stackoverflow.com/u/538697/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Dynamodb global secondary index composite sort key

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Global Secondary Indexes in DynamoDB

If you're working with Amazon DynamoDB and trying to optimize data retrieval, you may have come across the concept of Global Secondary Indexes (GSI). Utilizing GSIs can significantly improve your application's ability to query data using different access patterns. A common challenge for new users is figuring out how to set up a GSI, particularly one that includes a composite sort key. Let’s dive into this topic together.

The Problem

You’ve created a primary table in DynamoDB to store orders, consisting of various fields such as User_ID, ID, Type, Product_name, Total_Value, and Created_at. The primary key structure is simple, with User_ID as the partition key and Created_at as the sort key. This allows you to retrieve orders by a specific user based on when they were created.

However, your application also requires an additional access pattern where you can retrieve all orders filtered by Product_name and Type, while sorting the results by Total_Value and Created_at. This is where you decided to create a GSI. Your initial plan for the GSI includes:

Partition Key: Product_name

Sort Key: Type# Total_value# Created_at

But you encounter an error when attempting to create the GSI: "Global Secondary Index range key not specified in Attribute Definitions. Type unknown."

The Solution

Let's break this down into actionable steps to successfully create a GSI with a composite sort key in DynamoDB.

Step 1: Understand Attribute Requirements

When you define a GSI, you must specify all attributes used in the index in the Attribute Definitions of the table. This means that any attribute that forms part of the composite sort key must also be defined in your primary table’s schema.

Since your intended sort key is composed of multiple attributes (Type, Total_value, and Created_at), DynamoDB does not automatically concatenate these values for you.

Step 2: Create a New Attribute for the Sort Key

Instead of trying to use a composite string format directly, you should consider using a single attribute for the sort key in your GSI. This will involve creating a new attribute where you concatenate the values of Type, Total_Value, and Created_at yourself. Here’s a way to conceptualize it:

New Attribute Name: You can name it something like Composite_Sort_Key.

Construct Value: In your application logic, whenever you save an order to the database, concatenate the values for Type, Total_Value, and Created_at using a separator. For example: Type# 100.00# 2023-05-01T12:00:00Z

Step 3: Index Creation

After you have ensured the new attribute is part of your table structure and data is being saved correctly:

Go to the AWS Management Console.

Navigate to your DynamoDB table.

Choose the option to create a new Global Secondary Index.

Set Partition Key as Product_name and Sort Key as Composite_Sort_Key.

Step 4: Update Application Logic

Make sure to update your application code where orders are created or updated to include the new concatenated value for the Composite_Sort_Key. This step is crucial as it ensures that the right data gets pushed to your GSI.

Final Thoughts

Creating a Global Secondary Index with a composite sort key in DynamoDB may present some challenges, especially when it comes to how the data is structured and indexed. However, by understanding the requirements and implementing a strategy to manage your sort keys effectively, you can customize access patterns to better suit your application's needs. Remember, thorough planning during the design stage can save a lot of headaches later on!

Now you're all set to create your GSI with a composite sort key in DynamoDB. Happy coding!