Query does not return some items from DynamoDB via GraphQL

Question

May I please know what is the reason why are items in DynamoDB not being fetched by GraphQL?

When searching via the DynamoDB console interface, I could easily see and query the item in there but once used in GraphQL, some items are not showing. Mind you, this isn't a connection problem because I could query items its just there's a specific item that is not being returned.

For example, if I query all Posts, it will return all posts in an array but the item is not showing there. However, when I try to query a Post just by targetting it by its ID, it is working well.

Example code that is not working:

listPosts(filter: {groupID: {eq: "25"}}) {
    items {
        id
        content
    }
}

but when I do this, it is working well:

getPost(id: "c59ce7e9") {
    id
    content
}

If it is giving other data except one perticular item. Then it's a problem at dynamo db side. May be you can double check the groupid stored in db for that item. Might be some type issue. — rajesh, Jul 02 '21 at 10:16

score 1 · Answer 1 · edited Aug 03 '21 at 23:32

I had this same issue and can share what i found and worked for me.

The default resolver for the list operation has a limit:20 built in.

{
  "version": "2017-02-28",
  "operation": "Scan",
  "filter": #if($context.args.filter) $util.transform.toDynamoDBFilterExpression($ctx.args.filter) #else null #end,
  "limit": $util.defaultIfNull($ctx.args.limit, 20),
  "nextToken": $util.toJson($util.defaultIfNullOrEmpty($ctx.args.nextToken, null)),
}

I imagine you could change this or you could add a limit filter to your query like this:

listPosts(filter: {groupID: {eq: "25"}}, limit:100) {
    items {
        id
        content
    }
}

The limit should be higher than the number of records.

You can see that this would be an issue because it is using the scan operation meaning it inspects each record for a match. this would hurt performance. you could add pagination or you should craft a query for this. you will need to look into pagination, relations and connection.

https://docs.aws.amazon.com/appsync/latest/devguide/designing-your-schema.html#advanced-relations-and-pagination

Query does not return some items from DynamoDB via GraphQL

1 Answers1