A transaction starts when a request arrive and it is committed when a
request returns. If there is an error that it not caught the
transaction is rolledback.
You can insert db.commit() (and db.rollback()) everywhere to break the
transaction in smaller parts.
Massimo
On Dec 29, 8:54 pm, toomim <too...@gmail.com> wrote:
> Mossimo, unfortunately this proposal does not solve the multi-
> threading problem.
>
> Can you tell me what the semantics of the "implicit begin" is? The
> problem is that I do not know where begin is inserted. I thought it
> happened at the beginning of every controller function call. That
> would make it impossible to do multiple transactions (with multiple
> begins) inside a single function. Is that assumption incorrect?
>
> On Dec 29, 1:14 pm, mdipierro <mdipie...@cs.depaul.edu> wrote:
>
> > Attention. There is no db.begin(). it is implicit. You can commit
> > automatically but why not:
>
> > while queue is not empty:
> > task = db(~status.belongs(('done','failed'))).select(limitby=
> > (0,1))[0]
> > success = do_long_thing(task)
> > if success:
> > task.update(status = 'done')
> > else:
> > task.update(status = 'failed')
>
> > On Dec 29, 2:10 pm, toomim <too...@gmail.com> wrote:
>
> > > Very clever, thank you! If it crashes, these items will be lost
> > > though. Is there a way to use transactions, to pull a single item at
> > > a time from the table, process and delete it, within a single
> > > transaction? Something like this:
>
> > > while queue is not empty:
> > > db.begin()
> > > task = db(status != 'done').select(limitby=(0,1))[0]
> > > task.update(status = 'done')
> > > success = do_long_thing(task)
> > > if success:
> > > db.commit()
> > > else:
> > > db.rollback()
>
> > > This way if the code fires an exception, or the computer crashes, the
> > > database will roll back to its prior state automatically. The problem
> > > is there is no begin statement in web2py. All begin statements seem
> > > to be automatic. Is it possible to do one manually? Can I turn off
> > > the automatic one?
>
> > > On Dec 29, 12:04 am, Thadeus Burgess <thade...@thadeusb.com> wrote:
>
> > > > Ah yes, so back to my original thought
>
> > > > db(status == 'pending').update(status = 'pending-' + request.now)
>
> > > > for db(status == 'pending-' + request.now).select():
> > > > task.update_record(status = 'processing-' + request.now
> > > > success = do_the_long_thing(task)
> > > > fail
> > > > if success:
> > > > task.update_record(status = 'done')
>
> > > > -Thadeus
>
> > > > On Tue, Dec 29, 2009 at 1:52 AM, toomim <too...@gmail.com> wrote:
> > > > > sk.update_record(status == 'proce
>
>
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