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https://issues.apache.org/jira/browse/JCR-926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12523852
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Jukka Zitting commented on JCR-926:
-----------------------------------
A central idea of the *Global* Data Store is that its global to the repository,
especially to drive down the costs of versioning and other cross-workspace
operations.
It would in principle be feasible to allow a workspace-specific data store to
be configured, but that would make handling of cross-workspace operations
considerably more complex. IMHO the benefits of workspace-local data stores
wouldn't be worth the added complexity.
On a longer timescale I also believe Jackrabbit should be moving even more to
centralized repository-global resource handling as that would for example help
a lot in making things like versioning operations transactional.
As for features like per-workspace quota or backups, I think those would be
best achieved by implementing the features in Jackrabbit instead of relying on
the underlying storage mechanism.
> Global data store for binaries
> ------------------------------
>
> Key: JCR-926
> URL: https://issues.apache.org/jira/browse/JCR-926
> Project: Jackrabbit
> Issue Type: New Feature
> Components: core
> Reporter: Jukka Zitting
> Attachments: dataStore.patch, DataStore.patch, DataStore2.patch,
> dataStore3.patch, dataStore4.zip, dataStore5-garbageCollector.patch,
> internalValue.patch, ReadWhileSaveTest.patch
>
>
> There are three main problems with the way Jackrabbit currently handles large
> binary values:
> 1) Persisting a large binary value blocks access to the persistence layer for
> extended amounts of time (see JCR-314)
> 2) At least two copies of binary streams are made when saving them through
> the JCR API: one in the transient space, and one when persisting the value
> 3) Versioining and copy operations on nodes or subtrees that contain large
> binary values can quickly end up consuming excessive amounts of storage space.
> To solve these issues (and to get other nice benefits), I propose that we
> implement a global "data store" concept in the repository. A data store is an
> append-only set of binary values that uses short identifiers to identify and
> access the stored binary values. The data store would trivially fit the
> requirements of transient space and transaction handling due to the
> append-only nature. An explicit mark-and-sweep garbage collection process
> could be added to avoid concerns about storing garbage values.
> See the recent NGP value record discussion, especially [1], for more
> background on this idea.
> [1]
> http://mail-archives.apache.org/mod_mbox/jackrabbit-dev/200705.mbox/[EMAIL
> PROTECTED]
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