AW: Re[2]: [OJB-developers] Re: OJB-ODMG does[n't] support implic it locking

[Mahler T. <tho...@it...>]

Hi Doug,

> -----Urspr=FCngliche Nachricht-----
> Von: Doug Currie [mailto:de...@fl...]
> Gesendet: Samstag, 2. Februar 2002 18:52
> An: Thomas Mahler
> Cc: ojb
> Betreff: Re[2]: [OJB-developers] Re: OJB-ODMG does[n't]=20
> support implicit
> locking
>=20
>=20
> Hello Thomas,
>=20
> Saturday, February 02, 2002, 6:35:51 AM, you wrote:
> <snip>
> TM> Hmm. If you are NOT using "read-uncommited" and there is no
> TM> READ-lock in the LockMap it must be a bug! Which isolation level
> TM> are you using for  class Article ?
>=20
> In two tests I used: <MappingRepository =
isolation=3D"repeatable-read">

Hmm, is this a typo? isolation must be declared per ClassDescriptor?

> as well as the usual repository.xml; both gave the same results. So
> yes, I think there's a bug.
>=20
> TM> Maybe we need different semantics for the isolation=20
> levels? Did you have=20
> TM> a look at my doc concerning the LockManager? It contains a table=20
> TM> demonstrating the behaviour of all isolation levels=20
> currently implemented.
>=20
> I will look at it more closely. I've hestitated to use the default
> read-uncommited isolation level because I don't understand the
> implications of the semantics. It's one thing to have transactions
> overlap; it's quite another to read a partially modified object. I am
> not that brave!
>=20

As a consequence of our discussion I placed a note on the feature list =
and
on the roadmap page stating that implicit locking is not fully =
implemented
and that users must use explicit lock to have proper tx isolation.

I assume we really need object clones per ODMG transaction to have a =
clean
optimistic locking.
Apropos: Jakob implemented locking and it is already integrated into =
the
latest 0.7.325 release!

Thomas

> Regards,
>=20
> e
>=20
>=20
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>=20