Cross Region APIs - Serverless App with Aurora Postgres - Latency Expectations

Hello.

The following document states that global database latency is less than 1 second.
No other published numbers were found in the documentation.
https://aws.amazon.com/rds/aurora/faqs/?nc1=h_ls

Can I have cross-region replicas with Amazon Aurora?
Yes, you can set up cross-region Aurora replicas using either physical or logical replication. Physical replication, called Amazon Aurora Global Database, uses dedicated infrastructure that leaves your databases entirely available to serve your application, and can replicate up to five secondary regions with typical latency of under a second. It's available for both Aurora MySQL-Compatible Edition and Aurora PostgreSQL-Compatible Edition.

As always, the answer to nearly any performance question is "it depends"... 😎. In your case, a lot will depend on the sizes of the average SQL statement sent from us-east-1 to us-east-2 and the result set sent back. For the lowest network latency across regions, you should peer your VPCs so everything goes across the AWS backbone (see the docs at https://docs.aws.amazon.com/vpc/latest/peering/what-is-vpc-peering.html for guidance).

The good news is your two regions are relatively close so the physics of a round-trip TCP/IP send/ack pair has pretty low latency simply due to the minimal distance. The site at https://latency.bluegoat.net/ does a pretty good job at showing average ping latencies for all commercial AWS region pairings. Their monitoring framework also uses VPC peering so the results, while only averages rather P50, P99, etc. values, look pretty accurate.