Maybe we ought to make pg_upgrade do this for you, but it won't happen
in 9.6, so call out the need for it as a migration consideration.
+
+
+ Update extension functions to be marked parallel-safe where
+ appropriate (Andreas Karlsson)
+
+
+ Many of the standard extensions have been updated to allow their
+ functions to be executed within parallel query worker processes.
+ These changes will not take effect in
+ databases
pg_upgrade>'d from prior versions unless
+ you apply ALTER EXTENSION UPDATE> to each such extension
+ (in each database of a cluster).
+
+
+