DVA-C02 Development with AWS Services Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The expression attribute values are incorrectly formatted

  Why it's wrong here

  The provided ExpressionAttributeValues format, ":orderId": {"S": "A123"}, is syntactically correct for specifying a string attribute value within a DynamoDB operation. In DynamoDB API calls, attribute values are represented as maps where the key indicates the data type (e.g., "S" for string, "N" for number, "BOOL" for boolean) and the value is the actual data. Therefore, the formatting itself is not the source of an error related to key conditions.

• ✓

  The table's partition key is not named 'OrderID'

  Why this is correct

  A DynamoDB Query operation fundamentally requires that its KeyConditionExpression explicitly references the table's defined partition key attribute. If the table's actual partition key is named something other than 'OrderID' (e.g., 'CustomerID' or 'PK'), then attempting to use 'OrderID' in the KeyConditionExpression will result in a ValidationException. This error occurs because the query is trying to apply a key condition to an attribute that is not recognized as the table's primary partition key.

• ✗

  The table does not exist

  Why it's wrong here

  If the specified DynamoDB table did not exist, the API call would typically return a ResourceNotFoundException. This error explicitly indicates that the table name provided in the request cannot be found in the AWS account and region. The context of the problem, which points towards an issue with the KeyConditionExpression not matching the table's schema, suggests that the table itself does exist, but the query parameters are misaligned with its definition.

• ✗

  The query needs to use a sort key

  Why it's wrong here

  While a DynamoDB table can optionally have a sort key in addition to its partition key, a Query operation does not strictly require the sort key to be included in the KeyConditionExpression. A query must specify the partition key, but it can retrieve all items associated with that partition key without further filtering by the sort key. Including the sort key is only necessary if you want to narrow down the results to a specific range or value within that partition.

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