I have two Oracle questions.

1. How can I set the primary key of a table when the table is made up of an object type? e.g.

   CREATE TABLE object_names OF object_type

2. I have created a Varray type,

   CREATE TYPE MULTI_TAG AS VARRAY(10) OF VARCHAR(10);

   but when I try to do

   SELECT p.tags.count FROM pg_photos p;

   I get an invalid identifier error on the "count" part. p.tags is a MULTI_TAG, how can I get the number of elements in the MULTI_TAG?