- Don't attempt to convert partial or expressional unique indexes
- Don't attempt to convert unique indexes based on a non-default
opclasses

- Untested prevention of conversion of non-btree indexes unique
indexes.  Untested as postgresql doesn't allow hash, gist, or rtree
based indexes to be unique.

rbt=# create unique index t on a using hash (col);
ERROR:  DefineIndex: access method "hash" does not support UNIQUE
indexes
rbt=# create unique index t on a using gist (col);
ERROR:  DefineIndex: access method "gist" does not support UNIQUE
indexes
rbt=# select version();
                                version
------------------------------------------------------------------------
 PostgreSQL 7.4devel on i386-unknown-freebsd4.8, compiled by GCC 2.95.4

Rod Taylor