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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

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Requirements

• user should be able to create a zone with partitions that have replicas on every node of the cluster that matches the zone filter and storage profiles;
• replicas should be operational in a case when they are not included into the consensus group, let’s call them learners. Learners are created on every node that matches the zone filters where regular replica is not created;
• read-write transactions work as on regular zones (i.e. through primary replicas);
• read-only transactions and SQL within read-only transactions use learners as regular non-primary replicas;
• filters and storage profiles for the zones having learners should work in the same way as for regular zones;
• auto scaling: if new nodes are included into the cluster, learners are created there automatically (if the nodes match the zone filters).

Proposal

Reference links

Tickets