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https://issues.apache.org/jira/browse/OAK-5192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15996632#comment-15996632
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Chetan Mehrotra commented on OAK-5192:
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bq. Maybe this is not working as expected? 48'047'720 bytes for just the lucene
index, if all of that is blobIds, is a lot of blobIds.
See [stats
here|https://issues.apache.org/jira/browse/OAK-2808?focusedCommentId=14511219&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14511219]
where total 86 GB of garbage was generated and 2 M index files removed in 7
days. So churn can be high
bq. 50 KB is just 0.005% of 1 GB. So you can save 0.005% of disk space with
that, right?
Yes. But what I think is happening here is that as Lucene files are immutable
the next 1.2GB would involve creation of 1.2GB file + deletion of 1 GB file. So
this would start adding up. We would need to see actual successive diff (from
the data where the stats were extracted) so validate that hypothesis.
> Reduce Lucene related growth of repository size
> -----------------------------------------------
>
> Key: OAK-5192
> URL: https://issues.apache.org/jira/browse/OAK-5192
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: lucene, segment-tar
> Reporter: Michael Dürig
> Assignee: Tommaso Teofili
> Labels: perfomance, scalability
> Fix For: 1.8, 1.7.3
>
> Attachments: added-bytes-zoom.png
>
>
> I observed Lucene indexing contributing to up to 99% of repository growth.
> While the size of the index itself is well inside reasonable bounds, the
> overall turnover of data being written and removed again can be as much as
> 99%.
> In the case of the TarMK this negatively impacts overall system performance
> due to fast growing number of tar files / segments, bad locality of
> reference, cache misses/thrashing when looking up segments and vastly
> prolonged garbage collection cycles.
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