From: David J. <dav...@ea...> - 2001-06-26 22:49:57
|
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: jbo...@li... > > [mailto:jbo...@li...]On Behalf Of > David > > Jencks > > Sent: Tuesday, June 26, 2001 5:38 PM > > To: jbo...@li... > > 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 > > > >> > > > > > > > > > > > > _______________________________________________ > > > Jboss-development mailing list > > > Jbo...@li... > > > http://lists.sourceforge.net/lists/listinfo/jboss-development > > > > > > > > > _______________________________________________ > > Jboss-development mailing list > > Jbo...@li... > > http://lists.sourceforge.net/lists/listinfo/jboss-development > > > > > > _______________________________________________ > Jboss-development mailing list > Jbo...@li... > http://lists.sourceforge.net/lists/listinfo/jboss-development > |