>>> On Wed, Aug 15, 2007 at  5:06 PM, in message <[EMAIL PROTECTED]>,
Tom Lane <[EMAIL PROTECTED]> wrote: 
> Robert Treat <[EMAIL PROTECTED]> writes:
>> I'm a little confused, wouldnt the transaction that waits 30 minutes before 
>> modifying data need to get an XID that jives with the system when it's 
>> transaction started, not when it began manipulating data?
> 
> Why?
> 
>> Would it really be safe to take a new snapshot at that time,
> 
> You wouldn't take a new snapshot.  The thought that occurs to me is that
> there's no reason that a transaction has to have an XID for itself
> before it takes a snapshot.  We always special-case our own XID anyway.

I'm having trouble picturing how that would work with a transaction using
the SERIALIZABLE transaction isolation level, or would this just be done at
the READ COMMITTED level?

-Kevin



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