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From Pinaki Poddar <ppod...@apache.org>
Subject Re: datacache
Date Tue, 27 May 2008 23:38:31 GMT

Hi Craig,
  Committed revision 660753 towards a model that
a) corrects refresh() behavior of single, clean entity
b) bypasses Data cache for refresh() altogether
c) throws away 'optimization' for a single entity

Pinaki


Craig L Russell wrote:
> 
> Hi Pinaki,
> 
> On May 27, 2008, at 3:00 PM, Pinaki Poddar wrote:
> 
>>
>> After some more analysis of refresh() issue...
>>
>> 1. it is observed that a refresh of a single, clean instance never  
>> hits the
>> database -- irrespective of whether Data Cache is active or not.  
>> That does
>> not appear spec compliant.
> 
> I agree.
>>
>>
>> 2. refresh() behaves differently on current lock level. With NO LOCK  
>> it
>> reads from Data Cache; on any stronger lock it hits the database.
>> I am of the opinion that all refresh() must bypass data cache  
>> altogether
>> always -- because refresh() seems to express explicit intent of the  
>> user to
>> read data from database (say when the application thinks that out-of- 
>> band
>> modifications may have taken place on the database).
> 
> I agree.
>>
>>
>> 3. There is an 'optimization' on BrokerImpl.refresh() -- one for a  
>> single
>> entity and other for a collection. Removing that optimization (which  
>> leaves
>> some maintenance concern of similar but not same code blocks) is  
>> another
>> suggestion.
> 
> Seems that if the user calls refresh on a single entity or on a  
> collection, then we should hit the database every time. Who are we to  
> know that the database hasn't changed in the last millisecond? Sure,  
> we're smart, but we're not omniscient.
> 
> Craig
>>
>>
>>
>> Comments?
>>
>>
>> -- 
>> View this message in context:
>> http://www.nabble.com/datacache-tp17326391p17501042.html
>> Sent from the OpenJPA Developers mailing list archive at Nabble.com.
>>
> 
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com
> P.S. A good JDO? O, Gasp!
> 
> 
>  
> 

-- 
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