PostgreSQL Equivalent of SQLServer's NoLock Hint

A SELECT doesn't lock any table in PostgreSQL, unless you want a lock:

SELECT * FROM tablename FOR UPDATE;

PostgreSQL uses MVCC to minimize lock contention in order to allow for reasonable performance in multiuser environments. Readers do not conflict with writers nor other readers.

I've done some research and it appears that the NOLOCK hint in SQL Server is roughly the same as READ UNCOMMITTED transaction isolation level. In PostgreSQL, you can set READ UNCOMMITTED, but it silently upgrades the level to READ COMMITTED. READ UNCOMMITTED is not supported.

PostgreSQL 8.4 documentation for Transaction Isolation: http://www.postgresql.org/docs/8.4/static/transaction-iso.html