var AWS = require("aws-sdk");
var dynamoDB = new AWS.DynamoDB.DocumentClient();

let params = {
    RequestItems: {
        "db-test": [
            {
                PutRequest: {
                    Item: {
                        R_TIMESTAMP: 'STRING_VALUE1' ,
                        R_ID: 'STRING_VALUE1'
                    }
                }
            },
            {
                PutRequest: {
                    Item: {
                        R_TIMESTAMP: 'STRING_VALUE2' ,
                        R_ID: 'STRING_VALUE2'
                    }
                }
            }
        ]
    }
};

dynamoDB.batchWrite(params, function(err, data) {
    if (err) {
        console.log("Error", err);
    } else {
        console.log("Success", data);
    }
})

Error { ValidationException: The provided key element does not match the schema
at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:51:27)