When you do a DynamoDB write it's replicating that write to 2 other datacenters before ACK (for availability + durability reasons). Your local Postgres instance

When you do a DynamoDB write it's replicating that write to 2 other datacenters before ACK (for availability + durability reasons). Your local Postgres instance doesn't need to make any network hops at all. DynamoDB handled >100M qps during prime day, and its storage is effectively infinite. You don't have to self manage sharding, failover, CDC, etc. disclaimer: I work for AWS (but not on DDB)