Thanks much for the input and direction guys!
I'm coding it in now, so we'll see how it works out. And yes, I had
missed the one little statement about the retrying of the transaction
until success.
Thanks again!
Sam
On Jul 15, 5:30 pm, Robert Kluin <robert.kl...@gmail.com> wrote:
> Yes it was. :)
>
> Robert
>
>
>
> On Wed, Jul 14, 2010 at 5:49 PM, Chris Copeland <ch...@cope360.com> wrote:
>
> > On Wed, Jul 14, 2010 at 3:54 PM, Sam <couponsys...@gmail.com> wrote:
>
> >> I believe all that it would do is
> >> move the timing issue from the main program logic to a defined
> >> transaction and we would still have the potential gap in time between
> >> when the initial query was executed to fetch the data and the put()
> >> was execute to write it back.
>
> > If the data fetched by the get() at the first of the transaction has been
> > changed (by another process) when you do the put() at the end of the
> > transaction, then the transaction will be retried and it will do a new get
> > which will see the other process's changes and the process repeats. This
> > isn't obvious, but it is talked about in one of the links I sent earlier.
>
> > I think Robert's example is missing a put() at the end of the transaction
> > function:
>
> > def txn():
> > ccode = CCode.all().filter('Assinged', 0)\
> > .filter('ExpireDate >=', dtCompareDate)\
> > .filter("PartnerID", intPartnerID).get()
> > if not ccode:
> > # handle no ccode....
> > ccode.SessionID = strSessionID
> > ccode.Assigned = 1
> > ccode.put()
>
> > db.run_in_transaction(txn)
>
> > -Chris
>
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