Hi Vasily,

Thanks for the email.

To answer your question: you should reset the application basically any
time you change the topology. Some transitions are safe, but others will
result in data loss or corruption. Rather than try to reason about which is
which, it's much safer just to either reset the app or not change it (if it
has important state).

Beyond changes that you make to the topology, we spend a lot of effort to
try and make sure that different versions of Streams will produce the same
topology, so unless the release notes say otherwise, you should be able to
upgrade without a reset.
I can't say right now whether those wacky behaviors are bugs or the result
of changing the topology without a reset. Or if they are correct but
surprising behavior somehow. I'll look into it tomorrow. Do feel free to
open a Jira ticket if you think you have found a bug, especially if you can
describe a repro. Knowing your topology before and after the change would
also be immensely helpful. You can print it with Topology.describe().

Regardless, I'll make a note to take a look at the code tomorrow and try to
decide if you should expect these behaviors with "clean" topology changes.


On Thu, Jul 12, 2018 at 11:51 AM Vasily Sulatskov <[EMAIL PROTECTED]>