Ole Streicher wrote:
>
> > > BTW, I tried to use TRANSACTION_READ_UNCOMMITTED (which is described
> > > in the manual)
> > I don't believe that read uncommitted is supported by PostgreSQL.
>
> Finally, I found out the same when searching the net. But, why the
> user's manual (9.2. "Transaction Isolation") states something
> different? I guess it should be corrected in the manual.
>
If I am not mistaken the SQL standard allows the implementations to use
an isolations level higher than the one specified. So although the
possible speed-up provided by this weaker level is not explored, the
guarantees are provided by the stronger one.
In other words, you must not rely on visibility provided by weaker
isolation levels, they only exist to allow faster processing.
--
Fernando Nasser
Red Hat Canada Ltd. E-Mail: fnasser@redhat.com
2323 Yonge Street, Suite #300
Toronto, Ontario M4P 2C9