The correct answer is C. Projection Expressions.
Projection Expressions allow you to specify which attributes should be included in the query result. In the context of DynamoDB, a Projection Expression can be used to select a subset of attributes to be returned when querying a table. This can help reduce the amount of data that needs to be read and transferred, improving performance and reducing costs.
In this case, if you want to return only the Color and Size attributes when querying the product details table, you can use a Projection Expression to specify those attributes. For example, the following code snippet shows how to use a Projection Expression in a query operation:
const AWS = require('aws-sdk'); const dynamodb = new AWS.DynamoDB(); const params = { TableName: 'ProductDetails', KeyConditionExpression: 'ProductID = :pid', ExpressionAttributeValues: { ':pid': { S: '12345' } }, ProjectionExpression: 'Color, Size' }; dynamodb.query(params, (err, data) => { if (err) { console.error(err); } else { console.log(data.Items); } });
In this example, the ProjectionExpression is set to 'Color, Size', which tells DynamoDB to only return those two attributes for each item that matches the specified KeyConditionExpression. The result of the query will be an array of objects, each containing only the Color and Size attributes for the corresponding item in the table.
Update Expressions, Condition Expressions, and Expression Attribute Names are all used in different contexts within DynamoDB, but none of them are relevant to the task of selecting specific attributes during a query operation.
