Unique and Primary Key Constraints

I'm going to change the pg_dump command to pull these constraints out of
pg_constaint where possible, creating the appropriate alter table add
constraint command (see primary key).


Should unique constraints created with 'create index' (no entry in
pg_constraint) be re-created via alter table add constraint, or via
create unique index? 

I prefer ...add constraint.  After a while (release or 2) removal of
create unique index all together.

Since index names are unique, and all unique and primary key constraints
have a matching name in pg_index there isn't a problem with name
conflicts.