Ravi Sir's Cards › AWS
Ordering and retries
This revision card explains Ordering and retries. It starts from the need that at-least-once delivery means duplicates; wrong key loses per-user order. It describes same partition key preserves order inside a shard. Consumers must be idempotent. The how-to section notes include eventId; dedupe in DynamoDB; do not assume exactly-once from the stream alone. An example on the card is payment tip events for one bill share billId key so sequence stays correct.
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What this card says
Why do we need it?
At-least-once delivery means duplicates; wrong key loses per-user order.
What is it?
Same partition key preserves order inside a shard. Consumers must be idempotent.
idempotent
How to do it
Include eventId; dedupe in DynamoDB; do not assume exactly-once from the stream alone.
Example
Payment tip events for one bill share billId key so sequence stays correct.