Hi all, I would like to init a discuss of "PIP 34: Add new subscribe type -- Key_Failover" here.
At present, there are 3 kinds of subscription modes: exclusive, shared, and failover. Shared mode subscription is used a lot, because consumers could effectively parallel consume messages of same partition. But using shared mode will not keep the message order of same key, It would be good to leverage share mode, while also keeping the ordering of messages. This Proposal trying to introduce a new subscribe type Key_Failover to extend shared type. By Key_Failover, one partition could have several consumers to parallel consume messages, while all messages with the same key will be dispatched to only one consumer. Here is the link contains more information of this PIP: https://github.com/apache/pulsar/wiki/PIP-34%3A-Add-new-subscribe-type-Key_Failover Thanks.
