[jira] Updated: (DERBY-3650) internal multiple references from different rows to a single BLOB/CLOB stream leads to various errors when second reference used.

["Mike Matrigali (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-3650?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Matrigali updated DERBY-3650:
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I don't remember what came up when I was first working on this, and have not done anything on it other than post the patch a long time ago.  I wasn't really happy with the complexity, and was hoping to come up with something better but never did.  

I don't plan on doing anything else with this patch but am happy if someone else wants to run with it.  

What I would really like to do is change the underlying implementation of streams coming out of the store so that they can easily be cloned completely and not have their state shared.   Basically store should return an object that
just has an id that can be used to open a new stream that is independent of 
other using that id to open the stream.   I think this could solve a number of 
problems with current undefined behavior of sessions accessing the same
clob multiple times.

I think this would build fine on top of the clone changes that Kristian is working on in DERBY-4520.

> internal multiple references from different rows to a single BLOB/CLOB stream leads to various errors when second reference used.
> ---------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3650
>                 URL: https://issues.apache.org/jira/browse/DERBY-3650
>             Project: Derby
>          Issue Type: Bug
>          Components: Network Client, SQL, Store
>    Affects Versions: 10.3.3.0, 10.4.1.3
>         Environment: Mac OSX 10.4
> JDK 1.5.0_13
> Hibernate EntityManager 3.2.1
>            Reporter: Golgoth 14
>         Attachments: cloning-methods.html, derby-3650-preliminary_2_diff.txt, derby-3650-preliminary_diff.txt, derby-3650_tests_diff.txt, Derby3650EmbeddedRepro.java, Derby3650FullClientRepro.java, Derby3650FullRepro.java, Derby3650Repro.java, DerbyHibernateTest.zip, testdb.zip, traces_on_FormatIdStream_alloc.txt, UnionAll.java
>
>
> Derby + Hibernate JPA 3.2.1 problem on entity with Blob/Clob
> Hi,
> I'm using Derby in Client - Server mode with Hibernate JPA EJB 3.0.
> When a query on an entity containing a Clob and some joins on other entites is executed, an exception with the following message is thrown:
>   XJ073: The data in this BLOB or CLOB is no longer available.  The BLOB/CLOB's transaction may be committed, or its connection is closed.
> This problem occurs when the property "hibernate.max_fetch_depth" is greater than 0.
> When hibernate.max_fetch_depth=0, the query works.
> If Derby is configured in embedded mode, the query works independently of the value of hibernate.max_fetch_depth.
> On the Hibernate's documentation, the advised value of hibernate.max_fetch_depth is 3.
> Could you explain me if I made something wrong ?
> Thank you.
> Stephane

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