Github user alpinegizmo commented on a diff in the pull request: https://github.com/apache/flink/pull/3258#discussion_r99369468 --- Diff: docs/ops/upgrading.md --- @@ -35,23 +35,105 @@ under the License. ## Upgrading the Flink Framework Version - - Either "in place" : Savepoint -> stop/cancel -> shutdown cluster -> start new version -> start job - - Another cluster variant : Savepoint -> resume in other cluster -> "flip switch" -> shutdown old cluster +This section describes the general way of upgrading Flink framework version from version 1.1.x to 1.2.x and migrating your +jobs between the two versions. + +In a nutshell, this procedure consists of 2 fundamental steps: + +1. Take a savepoint in Flink 1.1.x for the jobs you want to migrate. +2. Resume your jobs under Flink 1.2.x from the previously taken savepoints. + +Besides those two fundamental steps, some additional steps can be required that depend on the way you want to change the +Flink version. In this guide we differentiate two approaches to upgrade from Flink 1.1.x to 1.2.x: **inplace** upgrade and +**shadow copy** upgrade. + +For **inplace** update, after taking savepoints, you need to: + + 1. Stop/cancel all running jobs. + 2. Shutdown the cluster that runs Flink 1.1.x. + 3. Upgrade Flink to 1.2.x. on the cluster. + 4. Restart the cluster under the new version. + +For **shadow copy**, you need to: + + 1. Before resuming from the savepoint, setup a new installation of Flink 1.2.x besides your old Flink 1.1.x installation. + 2. Resume from the savepoints with the new Flink 1.2.x installation. + 3. If everything runs ok, stop and shutdown the old Flink 1.1.x cluster. + +In the following, we will first present the preconditions for successful job migration and then go into more detail +about the steps that we outlined before. + +### Preconditions + +Before starting the migration, please check that the jobs you are trying to migrate are following the +best-practises for [savepoints]({{ site.baseurl }}/setup/savepoints.html). In particular, we advise you to check that +explicit `uid`s were set for operators in your job. + +This is a *soft* precondition, and restore *should* still work in case you forgot about assigning `uid`s. +If you run into a case where this is not working, you can *manually* add the generated legacy vertex ids from Flink 1.1 +to your job using the `setUidHash(String hash)` call. For each operator (in operator chains: only head operator) you --- End diff -- only the head operator
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