Motivation

Replicated zones are zones with partitions that have replicas on every node of the cluster that matches the zone filter and storage profile filter. These zones can provide better performance on SQL joins. 

Currently in Apache Ignite 3, we have an ability to set any number of replicas for any zone regardless of its initial replica number. The problem is that in large clusters, if we create a zone with a number of replicas that would be equal to the cluster size, there will be too many members in each replication group to maintain consensus. This will have a serious impact on performance. Moreover, we don’t have automatic scale up for this case: if the user decides to scale up their cluster, they would need to change the replica number manually (unless it is big enough, exceeding the nodes number).

Therefore, we need special options for zones to create members of replication groups that would not be a part of consensus, and to be able to scale the zones along with the cluster.

Description

Risks and assumptions

Reference links

Tickets