[xwiki-devs] Suport for non versioned properties and more efficient saving

[Ludovic Dubost]

Yes.. The use case is to use this for storing information that is 
related to a wiki page but that at the same time can be update many many 
times and if we do it would create a huge amount of version and impact 
performance. Not being able to rollback would be a known behavior and 
this would be used for data that we are not interested in history of and 
that many times we could recalculate. In many cases it could be to store 
aggregate information that would be faster to access.

Example:

- last connection time of a user : it is only available using an 
aggregate query and could be costly to access if you wanted to show this 
next to each user. With a non versioned property you would have this in 
the user document cache.
- last update time of a feed in XWiki Watch and number of articles 
loaded (currently this generates tons of versions of the document and 
forces us to clear versions, thus potentially loosing important history 
information)
- average page rating or user rating (this is a requirement of the 
Socracy project http://www.socracy.org) calculated after each rating.
- watch list adding a page to watch for a user (not sure  if this one 
would be a use case as we might want the rollback for this)

These non versioned property could be updated using Groovy Notifications 
or could be updated using Groovy Scheduler Jobs..

The other requirement is about being more efficient when saving which 
also would allow XWiki to be more efficient for application with many 
saves on big documents with many objects and properties.

Ludovic

Vincent Massol wrote:
> This is a relatively big change and I think we need a vote for this.  
> At the very least Ludovic can you explain the need?
>
> This is the first time we would not version something and thus break  
> the "wiki" principle of rollback. Thus we need to be sure it's a valid  
> use case with this in mind.
>
> Thanks
> -Vincent
>
> On Jun 16, 2008, at 12:20 PM, Ludovic Dubost wrote:
>
>   
>> Artem,
>>
>> Can you look at integrating the following jira items in your schedule:
>>
>> http://jira.xwiki.org/jira/browse/XWIKI-2470
>> http://jira.xwiki.org/jira/browse/XWIKI-2471
>>
>> The objective would be to support non-versioned properties in XWiki  
>> Objects. Modifications to there properties would never make a new  
>> version of the document. At the same time we would highly improve  
>> our saving by not resaving data that are not changed. This would  
>> have great effect on big documents.
>>
>> If we had these in the standard API it would allow us not to write a  
>> separate plugin and storage on a client project.
>>
>> Ludovic
>>
>> -- 
>> Ludovic Dubost
>>     
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>   


-- 
Ludovic Dubost
Blog: http://blog.ludovic.org/
XWiki: http://www.xwiki.com
Skype: ldubost GTalk: ldubost