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Date: Fri, 5 Feb 2010 03:30:28 +0000 (UTC)
From: "Mamta A. Satoor (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Updated: (DERBY-4537) Update on tables with blob columns
 streams blobs into memory even when the blobs are not updated/accessed.
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     [ https://issues.apache.org/jira/browse/DERBY-4537?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mamta A. Satoor updated DERBY-4537:
-----------------------------------

    Attachment: derby4537Repro.java

Attaching a repro. Follow the steps below to see the behavior.


/**
 * Repro for DERBY-4537:
 * To reproduce the problem, try following steps
 * 1)First load the necessary data using following
 * java org.apache.derbyTesting.functionTests.tests.lang.derby4537Repro
 * 2)Now run ij with limited heap and try to update the table with
 * no blob columns and then table with blob column
 * java -Xmx4m -Dij.exceptionTrace=true org.apache.derby.tools.ij
 * connect 'jdbc:derby:testDB4537;create=true';
 * -- following will pass. t2 does not have blob column
 * update t2 set status = 1 where id = 1;
 * -- following will fail. t1 has blob column but we are not updating it
 * update t1 set status = 1 where id = 1;
 */

> Update on tables with blob columns streams blobs into memory even when the blobs are not updated/accessed.
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4537
>                 URL: https://issues.apache.org/jira/browse/DERBY-4537
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.6.0.0
>            Reporter: Mamta A. Satoor
>            Priority: Minor
>         Attachments: derby4537Repro.java
>
>
> While investigating DERBY-1482, I wrote a simple program to see the behavior of a simple update (without any triggers) of a table with blob columns. 
> The update is on a non-blob column of a table with blob volumns. 
> When this update is made with limited heap memory, Derby runs into OOM error. 
> I tried another table similar to earlier table but with no blob column. An update on that table does not run into OOM when run with same limited heap memory. 
> I would have expected the update to pass for table with blob column since we are not referencing/updating the blob column. But it appears that we might be streaming in blob column even though it is untouched by the update sql. 
> I wonder if working on this jira first will make the work for DERBY-1482 any easier or better yet, will it make the problem with DERBY-1482 go away? Will attach a reproducible program for this soon.

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