undefined | Better HN

0 pointsjolux4y ago0 comments

S3 is strongly consistent now: https://aws.amazon.com/s3/consistency/

0 comments

4 comments · 1 top-level

fizwhiz4y ago· 3 in thread

What a ridiculous marketing term. This is a RYW (Read your writes) level of consistency which is a far cry from Strong consistency (see https://jepsen.io/consistency). Seems like eventual consistency with some affinity bolted on.

joluxOP4y ago

That page does not give a hard definition for strong consistency, it says that it uses them informally as relative terms. AWS is not claiming serializability, they call it "strong read-after-write consistency." I don't see the problem here? S3 famously wasn't guaranteed to read data you had just written for a long time, and now it is. That's significant.

Here's more about the specifics: https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcom...

In particular:

> Any read (GET or LIST request) that is initiated following the receipt of a successful PUT response will return the data written by the PUT request.

So this is stronger than RYW (emphasis mine).

anonymousDan4y ago

I have always understood strong consistency to refer to linearizability or sequential consistency - i.e. all clients have the same view of the global order but with sequential consistency permitting slightly more flexibility in how operations of different clients can be reordered wrt each other.

1 more reply

couchand4y ago

> > Any read (GET or LIST request) that is initiated following the receipt of a successful PUT response will return the data written by the PUT request.

> So this is stronger than RYW.

I'm not sure that it is? The examples listed below that description only specify making an update and then immediately reading it back from the same process.

1 more reply

j / k navigate · click thread line to collapse

0 comments

4 comments · 1 top-level

fizwhiz4y ago· 3 in thread

What a ridiculous marketing term. This is a RYW (Read your writes) level of consistency which is a far cry from Strong consistency (see https://jepsen.io/consistency). Seems like eventual consistency with some affinity bolted on.

joluxOP4y ago

That page does not give a hard definition for strong consistency, it says that it uses them informally as relative terms. AWS is not claiming serializability, they call it "strong read-after-write consistency." I don't see the problem here? S3 famously wasn't guaranteed to read data you had just written for a long time, and now it is. That's significant.

Here's more about the specifics: https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcom...

In particular:

> Any read (GET or LIST request) that is initiated following the receipt of a successful PUT response will return the data written by the PUT request.

So this is stronger than RYW (emphasis mine).

anonymousDan4y ago

I have always understood strong consistency to refer to linearizability or sequential consistency - i.e. all clients have the same view of the global order but with sequential consistency permitting slightly more flexibility in how operations of different clients can be reordered wrt each other.

1 more reply

couchand4y ago

> > Any read (GET or LIST request) that is initiated following the receipt of a successful PUT response will return the data written by the PUT request.

> So this is stronger than RYW.

I'm not sure that it is? The examples listed below that description only specify making an update and then immediately reading it back from the same process.

1 more reply

j / k navigate · click thread line to collapse