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Subject: RE: Cayenne Transactions vs MySQL Transactions
Date: Thu, 28 Oct 2010 15:53:38 +0100
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Hi Michael,

Thanx for the answers. About point 1, when you talk about the =
'container', what
do you mean? So you're telling me the default transaction engine Cayenne =
uses is
from the DB, not managed by cayenne programmatically (cayenne calls =
BEGIN
TRANSACTION and COMMIT from the DB)?

About point 2, I was asking your opinion about the degree of reliability =
on
comparing cayenne's optimistic locking with lockings from the DB. Or do =
you mean
cayenne uses this mechanism straight from the DB? I was always a little =
confused
about if cayenne implemented these two mechanisms (transactions and =
locking) or
just called the proper methods from the DB.

Thanx a lot

Bruno

-----Mensagem original-----
De: Michael Gentry [mailto:mgentry@masslight.net]=20
Enviada: quinta-feira, 28 de Outubro de 2010 15:16
Para: user@cayenne.apache.org
Assunto: Re: Cayenne Transactions vs MySQL Transactions

1) Cayenne does a begin transaction and end transaction when it
commits (assuming you aren't using container-managed transactions, in
which Cayenne is deferring that operation to the container).  Are you
at least using InnoDB with MySQL?  MySQL hasn't had the best track
record for handling transactions/rollbacks.

2) I'd say optimistic locking is critical especially in a financial
application.  Maybe you wouldn't need/want it for a Facebook, but you
certainly want it when integrity of the data is important.  Cayenne's
optimistic locking is more reliable than using a version number or
time stamp column.

3) Are you really using MySQL for a financial application?  MySQL
likes to silently (without error) change data on you.  This can lead
to data loss without you ever knowing about it.

mrg


On Thu, Oct 28, 2010 at 9:54 AM, Bruno Ren=E9 Santos =
<brunorene@holos.pt> wrote:
> Hello all,
>
>
>
> First, sorry about so many doubts in so little time, but I=92m trying =
to decide
> how to do some things on my application concerning cayenne. So adding =
to my
> previous doubts, here goes some more doubts:
>
>
>
> 1. =A0 =A0 =A0 Do cayenne transactions guarantee consistency as MySQL =
transactions
> guarantee?
>
> 2. =A0 =A0 =A0 Do you think cayenne=92s optimistic locking is reliable =
enough to use
on
> a financial web application with money movements between accounts, =
where you
> could have lots of people messing with the same accounts? If not, how =
can use
a
> regular lock from the MySQL DB? With a performNonSelectingQuery?
>
>
>
> Thank you so much
>
> Bruno Santos
>
> --
>
>
>
> Bruno Ren=E9 Santos | Gestor de Projectos - Project Manager |
> <mailto:brunorene@holos.pt> brunorene@holos.pt | =
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