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https://issues.apache.org/jira/browse/NIFI-2854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15664036#comment-15664036
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ASF GitHub Bot commented on NIFI-2854:
--------------------------------------
Github user markap14 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1202#discussion_r87807516
--- Diff:
nifi-nar-bundles/nifi-provenance-repository-bundle/nifi-persistent-provenance-repository/src/main/java/org/apache/nifi/provenance/schema/FieldSerializer.java
---
@@ -0,0 +1,27 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.nifi.provenance.schema;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+
+import org.apache.nifi.provenance.ProvenanceEventRecord;
+
+public interface FieldSerializer {
--- End diff --
Yes - good catch.
> Enable repositories to support upgrades and rollback in well defined scenarios
> ------------------------------------------------------------------------------
>
> Key: NIFI-2854
> URL: https://issues.apache.org/jira/browse/NIFI-2854
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Core Framework
> Reporter: Mark Payne
> Assignee: Mark Payne
> Fix For: 1.1.0
>
>
> The flowfile, swapfile, provenance, and content repositories play a very
> important roll in NiFi's ability to be safely upgraded and rolled back. We
> need to have well documented behaviors, designs, and version adherence so
> that users can safely rely on these mechanisms.
> Once this is formalized and in place we should update our versioning guidance
> to reflect this as well.
> The following would be true from NiFi 1.2.0 onward
> * No changes to how the repositories are persisted to disk can be made which
> will break forward/backward compatibility and specifically this means that
> things like the way each is serialized to disk cannot change.
> * If changes are made which impact forward or backward compatibility they
> should be reserved for major releases only and should include a utility to
> help users with pre-existing data convert from some older format to the newer
> format. It may not be feasible to have rollback on major releases.
> * The content repository should not be changed within a major release cycle
> in any way that will harm forward or backward compatibility.
> * The flow file repository can change in that new fields can be added to
> existing write ahead log record types but no fields can be removed nor can
> any new types be added. Once a field is considered required it must remain
> required. Changes may only be made across minor version changes - not
> incremental.
> * Swap File storage should follow very similar rules to the flow file
> repository. Adding a schema to the swap file header may allow some variation
> there but the variation should only be hints to optimize how they're
> processed and not change their behavior otherwise. Changes are only permitted
> during minor version releases.
> * Provenance repository changes are only permitted during minor version
> releases. These changes may include adding or removing fields from existing
> event types. If a field is considered required it must always be considered
> required. If a field is removed then it must not be a required field and
> there must be a sensible default an older version could use if that value is
> not found in new data once rolled back. New event types may be added.
> Fields or event types not known to older version, if seen after a rollback,
> will simply be ignored.
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