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From Michael Dürig <mdue...@apache.org>
Subject Re: [jr3 microkernel] Write skew
Date Wed, 30 Nov 2011 17:47:43 GMT


On 30.11.11 17:13, Stefan Guggisberg wrote:
>> Good catch! Two points:
>>
>> 1) Does visible mean immediately visible on next access or visible after
>> refresh? The second case would work with snapshot isolation.
>>
>> 2) Event though I'd like it to be different, spec. compliance hasn't been a
>> top priority on this project so far.
>
> i guess what you mean by 'spec compliance' is 'support of all and every
> optional features in the JCR spec'. and i agree with that.
>
> jr3 should IMO be spec compliant in the sense that it passes the TCK.
> which optional features should be supported is TBD.

We should clarify that quickly then. AFAIU it form that list of 
goals/non-goals which is floating around on of the goals is "mvcc, only 
update sessions on refresh()" which is in direct violation of the spec.

Also a non-goal on that list is nodetype consistency which AFAIK would 
also violate the spec. As my example on the Wiki [1] shows, with 
snapshot isolation as it is currently implemented we will not be able to 
enforce node type consistency.

Michael

[1] 
http://wiki.apache.org/jackrabbit/Transactional%20model%20of%20the%20Microkernel%20based%20Jackrabbit%20prototype

>
> we don't need another JCR 2.0/2.1 reference implementation.
> we already have one with jackrabbit 2.x
>
> cheers
> stefan
>
>>
>> Michael
>>
>>
>>>
>>> [0]
>>>
>>> http://www.day.com/specs/jcr/1.0/7.1.3.4_Seeing_Changes_Made_by_Other_Sessions.html
>>> [1]
>>>
>>> http://www.day.com/specs/jcr/2.0/10_Writing.html#10.1.4%20Visibility%20of%20Changes
>>>
>>> Cheers,
>>> Alex
>>>
>>> --
>>> Alexander Klimetschek
>>> Developer // Adobe (Day) // Berlin - Basel
>>>
>>

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