Multiple Sort Key Fields on AWS Amplify GraphQL Index Not Working as Expected

Question

Hello, I've encountered an issue with AWS GraphQL index service. When I create an index with multiple sortKeyFields like this:
            @index(
                 name: "listTopicsByTypeAndRegion"
                 queryField: "listTopicsByTypeAndRegion"
                 sortKeyFields: ["topicType", "regionLevelThree"]
               )
And try to query in AppSync:
            query MyQuery {
              listTopicsByTypeAndRegion(
                status: ACTIVE
                topicTypeRegionLevelThree: {eq: {topicType: "1", regionLevelThree: "2-1-1"}}
                sortDirection: ASC
                nextToken: null
              ) {
                nextToken
                items {
                  id
                  status
                  topicType
                  regionLevelThree
                }
              }
            }
I always get empty results:
            {
              "data": {
                "listTopicsByTypeAndRegion": {
                  "nextToken": null,
                  "items": []
                }
              }
            }

The query returns no data even without the topicTypeRegionLevelThree parameter. However, when I remove one of the sortKeyFields, it works normally. The AWS documentation doesn't provide detailed explanation about this behavior.

I found a similar issue (#1438) on GitHub but it remains unresolved: 
https://github.com/aws-amplify/amplify-category-api/issues/1438

Has anyone encountered similar issues or knows how to resolve this? Any help would be appreciated.

re:Post Agent · Answer

The issue you're experiencing with multiple sort key fields in your AWS AppSync GraphQL API is not uncommon. When using multiple sort key fields in an @index directive, there are some limitations and specific behaviors to be aware of.

First, it's important to note that when you define multiple sort key fields, they are combined into a single composite sort key. In your case, "topicType" and "regionLevelThree" are combined into a composite sort key named "topicTypeRegionLevelThree".

When querying an index with multiple sort key fields, you need to provide conditions for all the fields in the order they are defined. In your query, you're using the "eq" operator, which requires an exact match for both fields. This might be too restrictive and could be the reason you're getting empty results.

To troubleshoot this issue:

1. Ensure that you have data in your table that exactly matches the conditions you're querying for.

2. Try using a more flexible query condition. Instead of "eq", you could use "beginsWith" to match partial values:

topicTypeRegionLevelThree: {beginsWith: {topicType: "1", regionLevelThree: "2-1-1"}}

3. If you need to query based on only one of the sort key fields, you might need to create separate indexes for each field.

4. Double-check that the data types of your sort key fields match what's defined in your schema.

5. Verify that the status field is indeed part of your partition key as implied by your query.

If these suggestions don't resolve the issue, you might be encountering a limitation or bug in the current implementation of multiple sort key fields in AWS Amplify. In that case, you may need to consider alternative index designs or reach out to AWS support for further assistance.  
**Sources**  
[Query - Amazon DynamoDB](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html)  
[Use Amplify with MySQL | AWS re:Post](https://repost.aws/questions/QUACsmc72WSkGhBNtdFQOewA/use-amplify-with-mysql)  
[Unauthorized running AppSync Query | AWS re:Post](https://repost.aws/questions/QUnPjlPXMqTjOmIx3fXv_ymw/unauthorized-running-appsync-query)

Multiple Sort Key Fields on AWS Amplify GraphQL Index Not Working as Expected

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