[flink] 16/20: [FLINK-12870][doc] Add missing warnings to schema evolution documentation

[tz...@apache.org]

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commit 641cbed1da37357b8c14a0cec5d33235bcf3a30f
Author: Alexander Fedulov <al...@ververica.com>
AuthorDate: Thu Jun 20 13:40:22 2019 +0200

    [FLINK-12870][doc] Add missing warnings to schema evolution documentation
    
    This closes #8806.
---
 docs/dev/stream/state/schema_evolution.md | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/docs/dev/stream/state/schema_evolution.md b/docs/dev/stream/state/schema_evolution.md
index aa8d41e..296fa06 100644
--- a/docs/dev/stream/state/schema_evolution.md
+++ b/docs/dev/stream/state/schema_evolution.md
@@ -106,4 +106,12 @@ Flink fully supports evolving schema of Avro type state, as long as the schema c
 One limitation is that Avro generated classes used as the state type cannot be relocated or have different
 namespaces when the job is restored.
 
+{% warn Attention %} Schema evolution of keys is not supported.
+
+Example: RocksDB state backend relies on binary objects identity, rather than `hashCode` method implementation. Any changes to the keys object structure could lead to non deterministic behaviour.  
+
+{% warn Attention %} **Kryo** cannot be used for schema evolution.  
+
+When Kryo is used, there is no possibility for the framework to verify if any incompatible changes have been made.
+
 {% top %}