este é o formato Postgres UPDATE JOIN:
UPDATE address
SET cid = customers.id
FROM customers
WHERE customers.id = address.id
Aqui estão as outras variações:http://mssql-to-postgresql.blogspot.com/2007/12/updates-in-postgresql-ms-sql-mysql.html
UPDATE address
SET cid = customers.id
FROM customers
WHERE customers.id = address.id