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https://issues.apache.org/jira/browse/JCR-926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Mueller updated JCR-926:
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Attachment: dataStore3.patch
With this patch, both the old style 'BLOBStore' and the new style 'DataStore'
implementations co-exist. The BLOBStore is used by default. To use the
DataStore, set the System Property org.jackrabbit.useDataStore to 'true' as in:
java -Dorg.jackrabbit.useDataStore=true ...
So this patch can be used to test the GlobalDataStore feature. All unit tests
pass.
There are still a few things missing: There is no garbage collection yet.
Almost each blob creates two new subdirectories (this works, but is a bit
slower, and means lots of directories; can be avoided maybe).
The abstract class BLOBFileValue is now called BLOBValue (because, it is now
not always a file). The old BLOBFileValue is now again named BLOBFileValue.
New class Base64ReaderInputStream for BufferedStringValue to avoid creating a
file when converting long Base64 strings to BINARY data. Actually the higher
performance is just a side effect; the main reason to implement this was
becuase the old constructor is based on a file resource and can't be used with
the DataStore.
> 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, 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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