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https://issues.apache.org/jira/browse/JCR-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13605071#comment-13605071
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Jukka Zitting commented on JCR-3534:
------------------------------------

> So JackrabbitValue.getContentIdentifier will not be supported in Oak, either?

It will, but the implementation may well be something like hash(revision + 
path) that can't be reversed for use in something like getValueByContentId().

> How if clustering is not an option ? [...] For various reasons both share the 
> same Data Store.

Since they already share the data store (which already requires custom 
configuration), I don't believe setting up one of the repositories (or even a 
third one reserved for such data migration purposes) as a cluster shared by 
both boxes would be an insurmountable issue.

I agree that an approach like getValueByContentId() is probably easier to 
implement in practice for such a case, but is the overhead high enough to 
justify the leak in the abstraction?

                
> Add JackrabbitSession.getValueByContentId method
> ------------------------------------------------
>
>                 Key: JCR-3534
>                 URL: https://issues.apache.org/jira/browse/JCR-3534
>             Project: Jackrabbit Content Repository
>          Issue Type: New Feature
>          Components: jackrabbit-api, jackrabbit-core
>    Affects Versions: 2.6
>            Reporter: Felix Meschberger
>         Attachments: JCR-3534.patch
>
>
> we have a couple of use cases, where we would like to leverage the global 
> data store to prevent sending around and copying around large binary data 
> unnecessarily: We have two separate Jackrabbit instances configured to use 
> the same DataStore (for the sake of this discussion assume we have the 
> problems of concurrent access and garbage collection under control). When 
> sending content from one instance to the other instance we don't want to send 
> potentially large binary data (e.g. video files) if not needed.
> The idea is for the sender to just send the content identity from 
> JackrabbitValue.getContentIdentity(). The receiver would then check whether 
> the such content already exists and would reuse if so:
> String ci = contentIdentity_from_sender;
> try {
>     Value v = session.getValueByContentIdentity(ci);
>     Property p = targetNode.setProperty(propName, v);
> } catch (ItemNotFoundException ie) {
>     // unknown or invalid content Identity
> } catch (RepositoryException re) {
>     // some other exception
> }
> Thus the proposed JackrabbitSession.getValueByContentIdentity(String) method 
> would allow for round tripping the JackrabbitValue.getContentIdentity() 
> preventing superfluous binary data copying and moving. 
> See also the dev@ thread 
> http://jackrabbit.markmail.org/thread/gedk5jsrp6offkhi

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