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From "Jukka Zitting (JIRA)" <j...@apache.org>
Subject [jira] Updated: (JCR-926) Global data store for binaries
Date Wed, 16 May 2007 11:14:16 GMT

     [ https://issues.apache.org/jira/browse/JCR-926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jukka Zitting updated JCR-926:
------------------------------

    Attachment: DataStore.patch

Attached (DataStore.patch) is a first draft of what such a data store could look like. The
main interface is simply:

    public interface DataStore {

        DataRecord getRecord(DataIdentifier identifier) throws IOException;

        DataRecord addRecord(InputStream stream) throws IOException;

    }

The patch contains a simple file-based implementation of this interface. See the javadocs
in the patch for more details.

I will proceed to propose a way to integrate this concept in the existing Jackrabbit core
if there's consensus that this approach is worth pursuing.

> 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
>
>
> 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/%3c510143ac0705120919k37d48dc1jc7474b23c9f02cbd@mail.gmail.com%3e

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