Are you fetching data from external APIs directly inside your user-facing Lambda functions? Stop. I was doing exactly this with the Plaid API for my AI Financial Agent, and it was destroying my application's performance.
External APIs are slow, prone to rate-limiting, and can go down without warning.
The Solution:
Today, I refactored my Lambda function to completely decouple data ingestion from data serving.
Instead of calling client.transactions_get() every time the React frontend makes a request, the Lambda now relies solely on Amazon DynamoDB for read operations.
Python
The Read Path is now Lightning Fast ⚡
def get_transactions_from_dynamo(user_id):
response = table.query(
KeyConditionExpression=Key('user_id').eq(user_id)
)
return [item for item in response.get('Items', []) if item.get('transaction_id') != 'METADATA']
How does new data get in?
I configured an Amazon EventBridge rule that triggers the Lambda once a day behind the scenes. The Lambda detects the aws.events source, hits the Plaid API, and silently updates DynamoDB.
By separating the Write path (Ingestion) from the Read path (Dashboard Querying), the application is now resilient, respects API quotas, and feels incredibly snappy for the end user.
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