[Solved] You implemented pagination in DynamoDB SDK but the query always returns the first page repeatedly. What is the most probable cause? let params = { TableName: 'Orders', Limit: 3 };... | DynamoDB

DynamoDB - with AWS SDK

You implemented pagination in DynamoDB SDK but the query always returns the first page repeatedly. What is the most probable cause?

let params = { TableName: 'Orders', Limit: 3 };
let data = await dynamoDbClient.query(params);
params.ExclusiveStartKey = data.LastEvaluatedKey;
data = await dynamoDbClient.query(params);
console.log(data.Items);

ANot updating params.ExclusiveStartKey before the second query

BUsing query instead of scan for pagination

CAssigning ExclusiveStartKey after the first query instead of before

DSetting Limit too low causing repeated first page

Step-by-Step Solution

Solution:

Step 1: Analyze code flow
The code runs the first query, then sets ExclusiveStartKey from LastEvaluatedKey, then runs the second query.
Step 2: Identify timing of setting ExclusiveStartKey
Since ExclusiveStartKey is set after the first query, the second query uses the correct key.
Step 3: Check if the key is valid
If LastEvaluatedKey is undefined or null, setting ExclusiveStartKey to it causes the second query to fetch the first page again.
Step 4: Most probable mistake
Not checking if LastEvaluatedKey exists before assigning it causes repeated first page.
Final Answer:
Assigning ExclusiveStartKey after the first query without validation -> Option C
Quick Check:
Check if LastEvaluatedKey is null before using [OK]

Quick Trick: Validate LastEvaluatedKey before setting ExclusiveStartKey [OK]

Common Mistakes:

MISTAKES

Ignoring null LastEvaluatedKey causing repeated pages
Confusing query and scan for pagination issues

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More DynamoDB Quizzes

You implemented pagination in DynamoDB SDK but the query always returns the first page repeatedly. What is the most probable cause?

Step 1: Analyze code flow

Step 2: Identify timing of setting ExclusiveStartKey

Step 3: Check if the key is valid

Step 4: Most probable mistake

Final Answer:

Quick Check:

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