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From "Thomas Mueller (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JCR-2857) Support sequential (non-random) node ids
Date Mon, 10 Jan 2011 15:10:48 GMT

    [ https://issues.apache.org/jira/browse/JCR-2857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12979597#action_12979597

Thomas Mueller commented on JCR-2857:

Revision 1057220 and revision 1057229.

The feature is disabled by default. If the system property "jackrabbit.sequentialNodeId" is
set to "true", then the most significant bits are set to a cryptographically secure random
number, except for the bits that normally contain the UUID version number, which are set to
0 (so the node id can't clash with a version 1-5 UUID). That means the node id contains 56
bits of 'repository identifier'. This is good enough to run a few thousand cluster nodes;
the probability of duplicate repository identifiers is  about 0.00000003 for 65536 repositories.
But the feature doesn't provide the same guarantee for *globally* unique identifiers as normal
UUIDs do. If such a guarantee is required, the most significant bits could be set to the MAC
address (but in that case you could only use one repository per MAC address).

> Support sequential (non-random) node ids
> ----------------------------------------
>                 Key: JCR-2857
>                 URL: https://issues.apache.org/jira/browse/JCR-2857
>             Project: Jackrabbit Content Repository
>          Issue Type: Improvement
>          Components: jackrabbit-core
>            Reporter: Thomas Mueller
>            Assignee: Thomas Mueller
>         Attachments: jcr-2857.patch
> Currently, node ids are generated using a (cryptographically secure pseudo-) random number
generator. This has a many advantages (easy to implement, easy to merge nodes from multiple
repositories or cluster nodes), but is a performance bottleneck for large repositories.
> In addition to generating random node ids, Jackrabbit should support generating sequential
node ids.

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