What is the MOST cost-effective solution that the developer can implement to ensure that PutItem does not update an existing record?
Call the GetItem operation first to confirm that the record does not exist. Then call PutItem.
Enable the TTL attribute on the DynamoDB table.
Implement a conditional put by using the attribute_exists(transactionID) condition expression.
Implement a conditional put by using the attribute_not_exists(transactionID) condition expression.
Explanations:
Calling GetItem before PutItem introduces an unnecessary read operation, which increases cost and latency. DynamoDB’s conditional writes can ensure the item does not exist without needing an additional read.
Enabling TTL (Time to Live) would automatically delete items after a specified time, but it does not prevent duplicate entries from being written in the first place.
Usingattribute_exists(transactionID)ensures that the update happens only if the transactionID already exists. This would still result in updating existing records, which is not the desired behavior.
Theattribute_not_exists(transactionID)condition expression ensures that a new item is only added if the transactionID does not already exist, preventing the update of an existing record. This is the most cost-effective and efficient solution.
Based on what I know, the answer is:
Implement a conditional put by using the attribute_not_exists(transactionID) condition expression.