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https://issues.apache.org/jira/browse/OAK-2808?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chetan Mehrotra updated OAK-2808:
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Attachment: copyonread-stats.png
!copyonread-stats.png!
Above stats are taken from a system running from 7 days. As can be seen total
86 GB of garbage was generated and 2 M index files removed. So Lucene index
does create a lot more churn and would pose problem in deployments where Blob
GC is not run frequently or in shared data store scenarios.
/cc [~mmarth] [~tmueller] [~alexparvulescu]
> Active deletion of 'deleted' Lucene index files from DataStore without
> relying on full scale Blob GC
> -----------------------------------------------------------------------------------------------------
>
> Key: OAK-2808
> URL: https://issues.apache.org/jira/browse/OAK-2808
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: lucene
> Reporter: Chetan Mehrotra
> Fix For: 1.3.0
>
> Attachments: copyonread-stats.png
>
>
> With storing of Lucene index files within DataStore our usage pattern
> of DataStore has changed between JR2 and Oak.
> With JR2 the writes were mostly application based i.e. if application
> stores a pdf/image file then that would be stored in DataStore. JR2 by
> default would not write stuff to DataStore. Further in deployment
> where large number of binary content is present then systems tend to
> share the DataStore to avoid duplication of storage. In such cases
> running Blob GC is a non trivial task as it involves a manual step and
> coordination across multiple deployments. Due to this systems tend to
> delay frequency of GC
> Now with Oak apart from application the Oak system itself *actively*
> uses the DataStore to store the index files for Lucene and there the
> churn might be much higher i.e. frequency of creation and deletion of
> index file is lot higher. This would accelerate the rate of garbage
> generation and thus put lot more pressure on the DataStore storage
> requirements.
> Discussion thread http://markmail.org/thread/iybd3eq2bh372zrl
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