[infinispan-dev] Re: [horizon-dev] serializable isolation level

[Manik Surtani]

NOTE: CC'ing infinispan-dev at lists.jboss.org instead of horizon-dev at lists.jboss.org

Comments inline:

On 7 Apr 2009, at 15:35, Mircea Markus wrote:

> Manik Surtani wrote:
>>
>> On 7 Apr 2009, at 15:07, Mircea Markus wrote:
>>
>>> Hi,
>>>
>>> As we do support serializable isolation level in horizon
>>
>> No we don't.  See the javadocs on the IsolationLevel enum.
> Why are we even allowing a used to specify a SERIALIZABLE isolation  
> level if we simply do not support it? I can see most of the users  
> not reading the javadocs, and will be unpleased when seeing that a  
> phanthom read occurred, even though he/she specified SERIALIZABLE -  
> bad experience.

They are allowed to set what they like.  Setting any old gibberish  
throws a ConfigurationException, while setting a valid isolation level  
defined by the ANSI standard for ACIDity [1] is respected, but is  
either upgraded or downgraded to an isolation level we support (which  
is READ_COMMITTED and REPEATABLE_READ).  Appropriate WARNings are  
logged if an upgrade or downgrade takes place so IMO this isn't a bad  
user experience.  We state almost everywhere that we only support R_C  
and R_R.  If anyone expects to configure SERIALIZABLE, *not* look at  
the logs, and then expect things to work, well that's his problem.  :-)

[1] http://en.wikipedia.org/wiki/Isolation_%28database_systems%29

--
Manik Surtani
manik at jboss.org
Lead, JBoss Cache
http://www.jbosscache.org