Hi,
Ok, I was thinking of within one db. I'm working on a logical
inconsistency example if you change isolation within one db, but I don't
have it yet. I agree, if you have a loosely coupled distributed
transaction, even on one resource manager, the different branches can have
different isolation levels with no problems.
Do you have a suggestion for a declarative isolation specification that
will result in one isolation level/transaction-branch and be simpler than
using bmt? So far I can't think of one.
<flame-bait>I tend to think perhaps the best solution is to use a db that
gives you snapshot isolation with no performance penalty</flame-bait>
although perhaps this is not always possible.
david jencks
On 2001.06.26 17:49:42 -0400 Bill Burke wrote:
> Why can't a transaction manage different resources and each of those
> resources use a different transaction-isolation level? What's wrong with
> that?
>
> Bill
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of
> David
> > Jencks
> > Sent: Tuesday, June 26, 2001 5:38 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: [JBoss-dev] High load...
> >
> >
> > Hi,
> >
> > since you can't change the transaction isolation after you start the
> > transaction, the isolation is determined by the outermost isolation
> > specifier.
> >
> > david jencks
> >
> > On 2001.06.26 16:47:16 -0400 danch (Dan Christopherson) wrote:
> > > David Jencks wrote:
> > > Read on - the problem with this occured to a few of us already.
> > Although
> > > none of us mentioned putting it in the container-transaction - that's
> > > interesting. But what if a method at iso 'read-uncommitted' calls a
> > > method in an iso 'serializable' transaction?
> > >
> > > thanks,
> > > danch
> > >
> > > > Hi,
> > > >
> > > > Forgive me if I am talking nonsense, but doesn't it only make sense
> to
> > > have
> > > > transaction isolation per transaction???? I very much doubt you
> will
> > > find
> > > > a db that can support several transaction isolation levels within
> one
> > > > transaction. I can't quite figure out what it would mean, either.
> So
> > > I
> > > > say, put it with the transaction requirements for methods -
> Requires,
> > > > Requires New, etc. Then you can set the isolation each time you
> start
> > > a
> > > > new transaction, based on this specification.
> > > >
> > > > david jencks
> > > >
> > > > On 2001.06.26 14:48:00 -0400 Dain Sundstrom wrote:
> > > >
> > > >>>|I added transaction isolation to the new cmp plugin. You can set
> it
> > > by
> > > >>>|adding the <transaction-isolation> element after the datasource
> > > >>>
> > > >>element.
> > > >>
> > > >>>|Valid levels are:
> > > >>>| transaction-none
> > > >>>| transaction-read-committed
> > > >>>| transaction-read-uncommitted
> > > >>>| transaction-repeatable-read
> > > >>>| transaction-serializable
> > > >>>|
> > > >>>|Give me 10 minutes and I'll add it to JAWS...
> > > >>>
> > > >>>ok but these will be leveraged by new caches in JBoss 3.0
> > > >>>
> > > >>>
> > > >>>
> > > >>>so I would imagine that each application can set its own
> datasource
> > > >>>isolation level, (different kinds of bean). So it IS user
> > > configurable
> > > >>>right???
> > > >>>
> > > >>>Also how does it play with the datasources, if the datasource is
> > > shared
> > > >>>across applications and different tables support different locking
> > > >>>
> > > >>policies
> > > >>
> > > >>>(say one table is RO the other RW) can the driver support
> sequential
> > > >>>"setIsolationLevel" that only applies to the record and or table
> > > >>>
> > > >>touched?
> > > >>
> > > >>>marcf
> > > >>>
> > > >>>
> > > >>Right now this the jaws and jbosscmp code only support datasource
> per
> > > >>application. When we implement datasource per bean, we can have
> > > >>isolation
> > > >>level per bean. This leads to the intresting situation with EJB-QL
> > > >>queries
> > > >>that thouch multiput beans. May be we need to specify an isolation
> > > lever
> > > >>for
> > > >>each query. Havn't thought about it much. Right now you can only
> set
> > > it
> > > >>for the entire ejb-jar.
> > > >>
> > > >>Just tell me when you get the cache stuff figgured out and I
> > can update
> > > >>jaws
> > > >>and jbosscmp to support what ever you want.
> > > >>
> > > >>-dain
> > > >>
> > >
> > >
> > >
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