Re: Locking Modes

Hi Anthony,

regarding Oracle, a good news is that one of our new client is demanding
Oracle instead of Postgres. So I will have to test on both Oracle and
Postgres...

Franck

Le mardi 05 août 2008 à 15:21 +1000, Anthony Berglas a écrit :
> As I work through the Whitepaper I see that the locking modes have 
> become confused.
> 
> Locking and Isolation is very complex in general. And to understand 
> the real meaning of the different query options on the different 
> databases is a major undertaking. The documentation is generally 
> awful. I do know that using Oracle without FOR UPDATE in the default 
> isolation mode will cause corruptions.
> 
> I propose a simple approach.
> 
> 1. Optimistic locking always performed. Even if other modes 
> available. Ie. do our own locking because we don't trust the database.
> 
> 2. Session.setIsolationLevel added. Just calls through to 
> JDBC. SimpleORM does not change whatever default is used by the
> database.
> 
> 3. SOPTIMISTIC_UNCHECKED added back, so that certain fields that 
> cause grief can be excluded (eg. LONG type in Oracle).
> 
> 4. FOR UPDATE off by default.
> 
> Update Off by default is normally very dangerous. But having 
> optimistic locks backing it up should make it OK. People can then 
> add the FOR UPDATE mode when optimistic locks get broken too often.
> 
> I'm pretty sure that Hibernate gets this completely wrong. I'm 
> downloading Oracle and will do some tests.
> 
> Regards,
> 
> Anthony
> 
> Dr Anthony Berglas, [email protected] Mobile: +61 4 4838 8874
> Just because it is possible to push twigs along the ground with ones
> nose
> does not necessarily mean that is the best way to collect firewood.
> 
> 
> 
> 
>  



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