Penghui Il giorno lun 19 apr 2021 alle ore 15:11 PengHui Li <codelipeng...@gmail.com> ha scritto: > > Hi enrico, > > The delayed message feature is to support messages that can have any delay in > a single partition. > So, if the broker dispatches the messages based on the available time of the > message, this will break the FIFO order. > > So, if I understand correctly, "the behaviour of delayed messages even > for Exclusive subscriptions, still preserving a strict FIFO order” means > messages of a partition has same delay time? > If so, I think we can achieve this at the client-side(Just check the head > message is available or not)
At a high level I would like that the feature works well for the user, independently from how it is implemented, infact now it is difficult to explain to users that they may receive unexpected messages if they are using some "wrong" subscription type. Regarding a possible implementation I wonder if we can implement it at the broker side in order to save resources: - do not transfer the message if not needed - do not need to bounce back the message (negativeAck ?) in case that the message is not ready to be consumed Holding the message on the client until the message is deliverable is a bit complicated to implement and if we go this way we will have to implement it on every client (Java....) Enrico > > Thanks, > Penghui > On Apr 19, 2021, 8:00 PM +0800, Enrico Olivelli <eolive...@gmail.com>, wrote: > > Hi, > > I came across this great feature, Delayed Messages > > https://github.com/apache/pulsar/wiki/PIP-26:-Delayed-Message-Delivery > > > > And I see that this feature does not work with Exclusive and Failover > > subscriptions. > > The reason explained in the PIP is that this is because we want to > > guarantee FIFO order. > > > > I wonder if we could implement the behaviour of delayed messages even > > for Exclusive subscriptions, still preserving a strict FIFO order. > > > > Enrico
