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From "Andy Jefferson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (JDO-651) Modify specification to address NoSQL datastores
Date Mon, 17 Mar 2014 16:03:50 GMT

    [ https://issues.apache.org/jira/browse/JDO-651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13937948#comment-13937948

Andy Jefferson commented on JDO-651:

Clarification : 
When using optimistic txns commit/flush could still throw JDOOptimisticVerificationException
(since an implementation will not have applied the changes to the datastore, so can still
check the datastore for version updates before persisting) and rollback could throw away changes
if not yet flushed (i.e PDIRTY -> HOLLOW).
When using datastore txns then the implementation is at liberty to push changes to the datastore
at any time (just as it can for RDBMS) so commit/flush/rollback likely will be no-op (unless
the implementation is queuing changes of course). Once changes have been flushed then rollback
will be no-op (in terms of the datastore, since there is no way of backing the changes out).

> Modify specification to address NoSQL datastores
> ------------------------------------------------
>                 Key: JDO-651
>                 URL: https://issues.apache.org/jira/browse/JDO-651
>             Project: JDO
>          Issue Type: New Feature
>          Components: api, specification, tck
>    Affects Versions: JDO 3 (3.0)
>            Reporter: Matthew T. Adams
>            Assignee: Matthew T. Adams
>              Labels: jdo, nosql, profile, specification
>             Fix For: JDO 3 maintenance release 2 (3.2)
> There is increasing interest in NoSQL datastores (Google BigTable, Apache HBase, VMWare
Redis, etc), which not only do not support SQL, but also do not necessarily provide support
for traditional consistency or queriability features or guarantees, instead offering features
like eventual consistency, key-value storage mechanisms, etc.
> This request is to modify the JDO specification (and TCK & RI) so that it relaxes
certain portions of the specification, perhaps in the form of profiles similar to JavaEE 6
profiles, to allow datastores that may not support queries in general, do not support the
ACID requirements, or that support key-value-based storage mechanisms to be JDO-compliant.
 Additions to the specification may also be needed in order to directly address NoSQL-type
datastores, in a manner similar to its treatment of relational persistence mechanisms.
> Additionally, this request would serve to better support persistence on micro platforms
where consistency, queriability, etc, may not be supported.

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