News for hackers. Stuff that matters.

A comment on “Follow-The-Workload” Beats the Latency-Survivability Tradeoff in CockroachDB. Parent comment

Re:“Follow-The-Workload” Beats the Latency-Survivability Tra... by cube2222 on Friday December 08, 2017 @02:06AM (#15877202)
Without the consensus read you can get inconsistent values.

Suppose you write value a to leader A and then value b to leader A. Node B got both updates, node C got only the a value because of network timeouts.

Now you do a read from B of both values, you get the current a and b. Then you do a read from C, you receive the current a and the old b. Inconsistent.

Basically a violation of serializability and linearizability across the cluster in respect to the client.

[ Parent | on HN ]
Re:“Follow-The-Workload” Beats the Latency-Survivability Tra... by toolslive on Monday December 11, 2017 @12:22PM (#15898512)
No. In your example, value 'a' will not have been applied to the store in C yet, as there is a hole in the log: a set of updates that contains update 'b' (and possibly others). So the view in A will be more up to date than the view in C, but both will be consistent.
[ Parent | on HN ]