What I need to do: Update a column in on one entity based on another entities column value when adding or updating the second entity Entity one is an account record with a balance The new or updated entity is a transaction record against that account I want to update the balance on the account record based on the value of the new transaction, or an update on the value of the transaction I saw TransactWriteItems as a possible solution, but this appears to update records with the same key values? So my question is, should I be doing this via consecutive calls in the front end, ie add or update the transaction, and on “success” make a second call to update the account balance, or is there something available to update both records in a single call?

You could make just make two update calls from the backend lambda

So on doing that, If the first call succeeds, and the second fails, add a rollback type call in a catch to revert the first put/update?

Potentially, if you truly need a transaction you could use TransactWriteItems (I've not familiar with it myself but is intended for your use case) There's an example here

Nice. I was looking at that feature, but did not see an example like the one you posted. That is exactly what I need, since it will automatically handle a fail all case. I will keep digging into that. Thank you, so much

Excellent, you're welcome

Digging through some stackoverflow and documentation Since sst is using DocumentClient, TransactWrite is the way to go, vs TransactWriteItems. https://stackoverflow.com/questions/55618285/having-some-trouble-with-dynamodb-transactwriteitems https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB/DocumentClient.html https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB/DocumentClient.html#transactWrite-property