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https://issues.apache.org/jira/browse/OAK-4279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15312132#comment-15312132
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Michael Dürig commented on OAK-4279:
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My main point is that the segment writer already de-duplicates segment blobs.
So there is no need to add de-duplication logic on top of this again.
Regarding IO, my point was comparing large blobs ({{new SegmentBlob(blobStore,
duplicateId).equals(sb)}}). This is really expensive for large ones unless they
are not equal.
I think we should compare performance, efficiency and heap usage of OC with and
without caching of binaries to get a clear picture.
> Rework offline compaction
> -------------------------
>
> Key: OAK-4279
> URL: https://issues.apache.org/jira/browse/OAK-4279
> Project: Jackrabbit Oak
> Issue Type: Task
> Components: segment-tar
> Reporter: Michael Dürig
> Assignee: Alex Parvulescu
> Priority: Blocker
> Labels: compaction, gc
> Fix For: 1.6
>
> Attachments: OAK-4279-checkpoints.patch, OAK-4279-v0.patch,
> OAK-4279-v1.patch, OAK-4279-v2.patch, OAK-4279-v3.patch, OAK-4279-v4.patch
>
>
> The fix for OAK-3348 broke some of the previous functionality of offline
> compaction:
> * No more progress logging
> * Compaction is not interruptible any more (in the sense of OAK-3290)
> * Offline compaction could remove the ids of the segment node states to
> squeeze out some extra space. Those are only needed for later generations
> generated via online compaction.
> We should probably implement offline compaction again through a dedicated
> {{Compactor}} class as it was done in {{oak-segment}} instead of relying on
> the de-duplication cache (aka online compaction).
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