Work in progress

42_advanced_configuration_management/40_node_properties.txt

@@ -69,7 +69,13 @@ The resulting properties will be:
 `"sysctls_postgresql":{"kernel.shmmax":"5368709120"}` and
 `"vm":{"vm.dirty_ratio":"10"}`
 
-`sysctls_postgresql` has been overriden by local property, and `vm` has been left untouched
+`sysctls_postgresql` has been overriden by local property, and `vm` has been left untouched.
+Note that it is an override, as the semantic of merging is not deterministic with literal values, and it does not allow to unset values. If you need to merge, please refer to the next paragraph.
+
+
+==== Merging properties
+
+If you want to merge server defined properties with local defined properties, rather than override them, you will need to use the generic method variable_dict_merge_tolerant to define how to merge properties.
 
 
 ==== Under the hood