Cassandra read consistency LOCAL_QUORUM

Question

I have a doubt about how does Cassandra return the value in case of LOCAL_QUORUM. If due to some case there is no quorum consensus between the values returned by individual nodes, will Cassandra not return any value at all or return the lastest value based on the timestamp.

Answer 1

Cassandra does not use consensus of the values, for quorum reads, to determine which value to return to the client, it always uses the timestamp value to determine the most recent value.

This most recent value is then used to overwrite the values in the other replicas using read repair, if the values do not match.

Answer 2

Cassandra always works based on timestamp and return the latest value to the client.After checksum read repair updates the replica for that partition. https://academy.datastax.com/support-blog/read-repair