[jira] [Commented] (OAK-5885) segment-tar should have a tarmkrecovery command

["Michael Dürig (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-5885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053773#comment-16053773 ] 

Michael Dürig commented on OAK-5885:
------------------------------------

The problem with the previous tooling was that it couldn't guarantee that the returned segment ids where in reverse chronological order. They would be in most cases but when written by different {{SegmentBufferWritters}} concurrently this wasn't guaranteed. 

To fix this we need to keep a (soft) link from each head super root records to its predecessor. This could either be done by introducing a new record type for super root records or by adding a property to the super root recording with that information. The former approach would require us to bump the segment format version while staying backwards compatible with the previous version. The latter approach would not require a segment version bump but rely on heuristics to detect super roots (by checking the presence of the right child nodes and properties). Given the minor priority of this issue and the fact that the previous version of this tooling also had the limitation re. heuristics I would opt. for the latter approach. 

> segment-tar should have a tarmkrecovery command
> -----------------------------------------------
>
>                 Key: OAK-5885
>                 URL: https://issues.apache.org/jira/browse/OAK-5885
>             Project: Jackrabbit Oak
>          Issue Type: Task
>          Components: run, segment-tar
>            Reporter: Andrei Dulceanu
>            Assignee: Andrei Dulceanu
>            Priority: Minor
>              Labels: tooling
>             Fix For: 1.8, 1.7.6
>
>
> {{oak-segment}} had a {{tarmkrecovery}} command responsible with listing candidates for head journal entries. We should re-enable this also for {{oak-segment-tar}}.
> /cc [~mduerig] [~frm]



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