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https://issues.apache.org/jira/browse/OAK-4649?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Francesco Mari updated OAK-4649:
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Summary: Move index files outside of the TAR files (was: Decouple segments
and indexes from TAR files)
> Move index files outside of the TAR files
> -----------------------------------------
>
> Key: OAK-4649
> URL: https://issues.apache.org/jira/browse/OAK-4649
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: segment-tar
> Reporter: Francesco Mari
> Assignee: Francesco Mari
>
> TAR files currently embed three indexes: an index of the segments contained
> in the TAR files, a graph index and an index of external binary references.
> Index files are checked for consistency purposes at the startup of the
> system. Normally, if an index file is corrupted it is recreated. Since the
> index file is contained inside the TAR file, recreating them implies
> rewriting the whole TAR file and appending the new index.
> This process creates unnecessary backups, since the biggest part of the TAR
> file is effectively immutable. Moreover, because index files are stored in
> the TAR files, we can't treat TAR files as true read-only files. There is
> always the possibility that they have to be opened again in write mode for
> the recovery of the index file.
> I propose to move those index files outside of the TAR files. TAR files will
> end up being truly read-only files containing immutable data, and index files
> will be granted their own physical files on the file system. Being index
> files derived data, they now can be recreated at will without impacting the
> read-only part of the segment store.
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