Simple task with partitioning which I can't realize

Hello all -

I have a task which is simple at the first look. I have a table which
contains hierarchy of address objects starting with macro region end ends
with particular buildings. You can imagine how big is it.

Here is short sample of table declaration:

create table region_hierarchy(

gid uuid not null default uuid_generate_v1mc(),

parent_gid uuid null,

region_code int2,

.

constraint pk_region_hierarchy primary key (gid),

constraint fk_region_hierarchy_region_hierarchy_parent foreign key
(parent_gid) references region_hierarchy(gid)

);

Being an Oracle specialist, I planned to using same declarative partitioning
by list on the region_code field as I did in Oracle database. I've carefully
looked thru docs/faqs/google/communities and found out that I must include
"gid" field into partition key because a primary key field. Thus partition
method "by list" is not appropriate method in this case and "by range"
either. What I have left from partition methods? Hash? How can I create
partitions by gid & region_code by hash? Feasible? Will it be working
properly (with partition pruning) when search criteria is by region_code
only? Same problem appears when there is simple serial "id" used as primary
identifier. Removing all constraints is not considered. I understand that
such specific PostgreSQL partitioning implementation has done by tons of
reasons but how I can implement partitioning for my EASY case? I see the
only legacy inheritance is left, right? Very sad if it's true.

Your advices are very important.

Thanks in advance.

Andrew.