How to avoid breaking states when upgrading Flink job?

Posted by Josh on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/How-to-avoid-breaking-states-when-upgrading-Flink-job-tp7726.html

Hi all,

Is there any information out there on how to avoid breaking saved states/savepoints when making changes to a Flink job and redeploying it?

I want to know how to avoid exceptions like this:

java.lang.RuntimeException: Failed to deserialize state handle and setup initial operator state.
	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:551)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: com.me.flink.MyJob$$anon$1$$anon$7$$anon$4

The best information I could find in the docs is here:

https://ci.apache.org/projects/flink/flink-docs-master/apis/streaming/savepoints.html

Having made the suggested changes to my job (i.e. giving a uid to every stateful sink and map function), what changes to the job/topology are then allowed/not allowed? 

If I'm 'naming' my states by providing uids, why does Flink need to look for a specific class, like com.me.flink.MyJob$$anon$1$$anon$7$$anon$4 ?

Thanks for any advice,

Josh