Re: Strange situation with two tables.

On Wed, 2002-09-11 at 15:20, Henshall, Stuart - WCP wrote:
...
> > BEGIN...END)  None of the results of the transaction will be
> > visible to
> > other connections until the transaction is committed.
> >
> >
> I thought that was only the case when the transaction level was SERIALIZABLE
> I believe pg starts in READ COMMITED transaction level.
> http://www.postgresql.org/idocs/index.php?transaction-iso.html

To be sure, I just tested by explicitly setting the isolation level to
read committed and to serializable.  As I expected, an uncompleted
transaction is indeed invisible to other connections, whichever
isolation level is chosen.

In terms of the documentation page you referred to, reading uncommitted
rows is a "dirty read".  This is only possible at isolation level 'read
uncommitted', which PostgreSQL does not support.

You may be referring to phantom reads; these could be avoided, if they
are a problem, by explicitly setting the transaction isolation level to
serializable.

--
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight, UK
http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839  932A 614D 4C34 3E1D 0C1C
                 ========================================
     "I am crucified with Christ; nevertheless I live; yet
      not I, but Christ liveth in me; and the life which I
      now live in the flesh I live by the faith of the Son
      of God, who loved me, and gave himself for me."
                                         Galatians 2:20