What does EXPLAIN show?
What proportion of contacts have owner_id=7 and user_id is null?
If it's a large number of contacts, I'd try the following:
create temporary table tusers as
select coalesce(p.ref_contact_id,e.ref_contact_id) as id, u.id as user_id
from my_users u
left join phone_numb
Currently I run two queries back-to-back to correlate users with contacts.
UPDATE contacts SET user_id = u.id
FROM my_users u
JOIN phone_numbers pn ON u.phone_significant = pn.significant
WHERE contacts.owner_id = 7 AND contacts.user_id IS NULL AND contacts.id =
pn.ref_contact_id;
UPDATE
