merlimat commented on issue #4012: Adding upsert functionality URL: https://github.com/apache/pulsar/pull/4012#issuecomment-481852631 > I didn't mean that the Pulsar cluster is not running. What I meant is that our end-to-end production message pipelines will be in a broken state. (i.e. Our customers will experience problems.) Consider a plumbing analogy. If you need to re-route pipes while water is flowing, if you can't do it extremely quickly, then water will end up leaking everywhere, and the people who are expecting water at a particular location will notice a loss of service. The purpose of the messaging system is to buffer up for these scenarios. Functions use a subscription associated that is used to retain the data when no consumers are connected. You have to plan the amount of disk space based on the time buffer you want to have in case of issues. During an update of the function there will be a quick restart of the process. If you want to minimize that time, you just need to have >1 instance per function. During the rolling upgrade there'll be always one function instance consuming from the topic.
---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
