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https://issues.apache.org/jira/browse/OAK-1804?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14016796#comment-14016796
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Jukka Zitting commented on OAK-1804:
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Looks good, +1 to commit.
Some improvements we could/should make after committing the patch:
* {{compact()}} should be private. It's better if we only publicly expose the
{{gc()}} method for this purpose.
* The log message written by {{compact()}} should probably be at INFO level,
it's IMO significant enough information.
* The {{writeNumber % compactThreshold == 0}} condition should also check for
{{writeNumber > 0}}.
* It would be better if the {{gc()}} method set only the {{compactNeeded}}
flag, which would trigger the {{compact()}} method to set {{cleanupNeeded}}.
This way we can guarantee that we won't end up with a compaction that's not
followed by the cleanup.
> TarMK compaction
> ----------------
>
> Key: OAK-1804
> URL: https://issues.apache.org/jira/browse/OAK-1804
> Project: Jackrabbit Oak
> Issue Type: New Feature
> Components: segmentmk
> Reporter: Jukka Zitting
> Assignee: Alex Parvulescu
> Labels: production, tools
> Fix For: 1.0.1, 1.1
>
> Attachments: SegmentNodeStore.java.patch, compact-on-flush.patch,
> compaction.patch
>
>
> The TarMK would benefit from periodic "compact" operations that would
> traverse and recreate (parts of) the content tree in order to optimize the
> storage layout. More specifically, such compaction would:
> * Optimize performance by increasing locality and reducing duplication, both
> of which improve the effectiveness of caching.
> * Allow the garbage collector to release more unused disk space by removing
> references to segments where only a subset of content is reachable.
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