On Thu, Aug 22, 2019 at 7:44 PM Deng Joey <deng...@hotmail.com> wrote:
> Hi, Pulsar Team, > > Could you please help to clarify the question as in the title for me? > > Here is the scene: > > 1. Assuming there are three partitions, and messages with a specified key > was sent to partition 1 using hash algorithm. > 2. Scale the partition to six, then messages with the same key might be > sent to different partition, e.g. partition 5. > 3. Now, we have messages with the key in both partition 1 and partition 5. > > In this case, do pulsar transfer the old messages in partition 1 to > partition 5 to make sure the consumer consumes the full message orderly? or does it use some other strategy? > Currently Pulsar doesn't have any guarantees between scaling up-and-down the number of partitions. With that being said, in your example, Pulsar doesn't copy the old messages in partition 1 to partition 5. With the newly introduced key_shared subscription, we are working on key-based ordering guarantee when scale up and down the number partitions. > > Thanks for the help. > > Best Regards, > > Joey Deng >
