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From Emmanuel Lecharny <>
Subject Re: TXN work update
Date Wed, 02 Nov 2011 09:27:26 GMT
On 11/2/11 10:10 AM, Selcuk AYA wrote:
> * When preparing txn log edits, I will need to log Modification and
> Attribute objects and keep them in memory for a while. Is it necessary
> to clone these objects while doing the logging at partition nexus
> level? In other words, will they be modified after reaching nexus
> level. I am thinking no but I wanted to check because I looked at
> changelog implementation and it does cloning.
>> Once at the nexus level, the elements won't be modified.
>> The ChangeLog stores (currently) data in memory, and those data are kept for
>> a while, so cross transactions. This is the reason why we clone the entry
>> and Attributes.
> with transactions, the attributes and modifications will be kept in
> memory cross transactions as well. But my understanding( and the thing
> I wanted to verify) is that Attributes, their Values and Modification
> objects should not change any more once they are at the Nexus level as
> these objects created per modification request and they are ready to
> be applied to  Entry objects.
Once in the nexus, the objects aren't modified.

About the changelog, you have to know that we keep them as long as we 
need the elements, but as we keep all of them, we are memory bound 
anyway. Also we don't need to keep the original entry in the changeLog, 
as we only have to apply the revert operation. The original entry is 
just needed to compute the reverse entry.

Emmanuel L├ęcharny

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