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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4537) Update on tables with blob columns streams blobs into memory even when the blobs are not updated/accessed.
Date Fri, 05 Feb 2010 19:14:27 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12830236#action_12830236
] 

Mamta A. Satoor commented on DERBY-4537:
----------------------------------------

I reran my test case with larger page cache size and as you suspected, now I do not see OOM.
I will go ahead and close this jira and not a bug.
$ java -Xmx4m -Dderby.storage.pageCacheSize=40 -Dij.exceptionTrace=true org.apac
he.derby.tools.ij
ij version 10.6
ij> connect 'jdbc:derby:testDB4537;create=true';
WARNING 01J01: Database 'testDB4537' not created, connection made to existing database instead.
ij> update t2 set status = 1 where id = 1;
1 row inserted/updated/deleted
ij> update t1 set status = 1 where id = 1;
1 row inserted/updated/deleted
ij> exit;

> 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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