Add an attribute to every item in a DynamoDB table with millions of items - amazon-dynamodb

Question

I am pretty new to AWS, but I need to add an attribute (and set the value to something) to every single item in a DynamoDB table.
I'm trying to write a generic script that will be able to do this to any table passed into it.
After a little bit of digging, it looks like I should be able to do this just by doing a scan of the table, getting the items, and then updating every single item.
My questions are:
(1) Does this seem like a reasonable approach?
(2) Is there an easier / better way to do this automatically? (a table-wide addition of an attribute to every item in the table?)

Answer 1

Yes it sounds reasonable, not ideal, but reasonable
Sure, there is always a better way, but this is an easy way, Here is a snippet I ran as a local JS file...
const AWS = require('aws-sdk');
const dynamoDb = new AWS.DynamoDB.DocumentClient({
region:'us-east-1'
});
async function main(event, context) {
let tableContents;
try{
//get items from dynamo
const params = {
TableName: `${YOUR_TABLE_NAME}`,
};
tableContents = await scanDB(params);
}catch(err){
console.log(err);
return err;
}
let calls = [];
tableContents.forEach(function(value){
let params = {
ExpressionAttributeValues: {
":newAttribute": false,
},
Key: {
"indexKey": value.indexKey
},
TableName: `${YOUR_TABLE_NAME}`,
UpdateExpression: "SET newAttribute = :newAttribute",
};
calls.push(dynamoDb.update(params).promise());
});
let response;
try{
response = await Promise.all(calls);
}catch(err){
console.log(err);
}
return response;
}
async function scanDB(params) {
let dynamoContents = [];
let items;
do{
items = await dynamoDb.scan(params).promise();
items.Items.forEach((item) => dynamoContents.push(item));
params.ExclusiveStartKey = items.LastEvaluatedKey;
}while(typeof items.LastEvaluatedKey != "undefined");
return dynamoContents;
};
main();
Good luck!