Db transactions and locking

Ian Kelly ian.g.kelly at gmail.com
Fri Nov 28 16:44:27 CET 2014


On Nov 27, 2014 4:39 PM, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Fri, Nov 28, 2014 at 5:02 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> > On Nov 27, 2014 4:26 AM, "Frank Millman" <frank at chagford.com> wrote:
> >> All Python database adaptors that I have used start a transaction when
you
> >> open a cursor. I have just re-read DB-API 2.0, and I cannot see
anything
> >> that specifies this behaviour, but AFAICT this is what happens.
> >
> > I don't know how others work, but cx_Oracle starts a transaction when
you
> > execute a statement, not when you open a cursor.
>
> Is there any material difference here? I mean, sure, you have a
> transaction, it'll show up in logs and stuff, but without any locks,
> it's unlikely to have much impact on the system. Unless you're
> creating and destroying a bunch of unnecessary cursors all the time,
> of course, but that'd be wasteful for other reasons.

Sure. If you commit the transaction and then execute another statement,
you'll get a new transaction.
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