diff options
Diffstat (limited to 'controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java')
-rw-r--r-- | controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java index 47c7b54264e..1f20bdf5533 100644 --- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java +++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/ApplicationSerializer.java @@ -54,6 +54,13 @@ import java.util.TreeMap; */ public class ApplicationSerializer { + // WARNING: Since there are multiple servers in a ZooKeeper cluster and they upgrade one by one + // (and rewrite all nodes on startup), changes to the serialized format must be made + // such that what is serialized on version N+1 can be read by version N: + // - ADDING FIELDS: Always ok + // - REMOVING FIELDS: Stop reading the field first. Stop writing it on a later version. + // - CHANGING THE FORMAT OF A FIELD: Don't do it bro. + // Application fields private final String idField = "id"; private final String createdAtField = "createdAt"; |