Re: More FOR UPDATE/FOR SHARE problems

>>> Bruce Momjian <bruce@momjian.us> wrote:
> Well, with no one replying, :-(, I went ahead and added to the Read
> Committed section of our manual to show a simple case where our read
> committed mode produces undesirable results.  I also did a little
> cleanup at the same time.
> 
> You can see the resulting text here:
> 
>http://momjian.us/tmp/pgsql/transaction-iso.html#XACT-READ-COMMITTED
So READ COMMITTED allows a single SQL statement to see and act upon a
database state which represents partial completion of a concurrent
database transaction?  I'm not sure whether the SQL spec explicitly
prohibits that, but it does seem surprising and potentially dangerous.
At a minimum, the documentation you suggest seems wise.  If that can
be prevented, I think it should be.  Seriously, this would justify
giving up the guarantee that serialization failures can't happen in
PostgreSQL in READ COMMITTED mode.  That guarantee is not required by
the standard, is not present in many databases, and to me it is less
important that accurate results.
-Kevin