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(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight, UK
http://www.lfix.co.uk/oliver
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