digoal(at)126(dot)com writes:
> postgres=# create extension btree_gist with schema pg_catalog;
I would say that that's neither a good idea nor a supported operation.
If it happens to work in some cases, okay, but you're definitely taking
risks of getting tripped up by the restrictions on pg_catalog...
> ERROR: 42501: permission denied to create "pg_catalog.new_type"
> DETAIL: System catalog modifications are currently disallowed.
... like that one.
regards, tom lane