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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5277) Intermittent OutOfMemoryErrors in BasicSetup.testTriggersWithLOBcolumns()
Date Tue, 21 Jun 2011 00:20:47 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13052286#comment-13052286
] 

Mamta A. Satoor commented on DERBY-5277:
----------------------------------------

Trigger action SPSes get marked invalid at the time of upgrade. When such a trigger fires
again, we regenerate the trigger action SPS. This regeneration looks at SYSTRIGGERS to find
out what columns are being used through the REFERENCING CLAUSE and uses them to find the relative
column positions of those columns in the regenerated trigger action. At the time of upgrade,
this information will be available in SYSTRIGGER if the trigger was 	created in 10.7.1.1.
But for all the other releases, SYSTRIGGERS does not have that 	information because that informaiton
was never collected for the triggers in those releases. Because of this, the regenerated trigger
action SPS will assume that all the columns will be read from the trigger table and hence
it will use the absolute column 	positions of those columns in the trigger table in the regenerated
trigger action SPS. 	This will cause such triggers to not be able to use the performance enhancement
of selective column reading from the trigger table and hence even though not all the columns
from the trigger table table are required by the triggering sql and firing triggers, we will
read all the columns. One fix for this can be that when a trigger fires and it finds that
it's trigger action SPS is invalid, then trigger should check if it uses REFERENCING clause
and if the trigger action column information is missing from the SYSTRIGGERS, then it should
drop and recreate the trigger with the trigger action column information collected and then
regenerate the trigger action SPS based on it. Doing this will make Derby not read the columns
not needed by the firing trigger and triggering sql. I will look into this to see what work
is involved in collecting the trigger action column information for the triggers with that
info missing. This should only happen for the triggers which are not created in 10.9 and higher
because only releases prior to 10.9 (with the exception of 10.7.1.1) didn't collect the information
about trigger action columns.


> Intermittent OutOfMemoryErrors in BasicSetup.testTriggersWithLOBcolumns()
> -------------------------------------------------------------------------
>
>                 Key: DERBY-5277
>                 URL: https://issues.apache.org/jira/browse/DERBY-5277
>             Project: Derby
>          Issue Type: Bug
>          Components: Test
>    Affects Versions: 10.9.0.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Mamta A. Satoor
>
> Seen many times in the JDK 7 tests lately, and also in the Tinderbox. First occurrence
was here: http://dbtg.foundry.sun.com/derby/test/Daily/jvm1.7/testing/testlog/sol32/1134678-suitesAll_diff.txt
> (There had been no commits in the last two days before this test run, so it's difficult
to say if a recent change caused it.)
> The test case has a comment that says that it should never read the LOB into memory,
but according to the stack trace, that's exactly what's happening:
> Caused by: java.lang.OutOfMemoryError: Java heap space
> 	at org.apache.derby.iapi.types.SQLBinary.readFromStream(Unknown Source)
> 	at org.apache.derby.iapi.types.SQLBinary.readExternal(Unknown Source)
> 	at org.apache.derby.iapi.types.SQLBinary.getValue(Unknown Source)
> 	at org.apache.derby.iapi.types.SQLBinary.loadStream(Unknown Source)
> 	at org.apache.derby.impl.sql.execute.UpdateResultSet.objectifyStream(Unknown Source)
> 	at org.apache.derby.impl.sql.execute.UpdateResultSet.collectAffectedRows(Unknown Source)
> 	at org.apache.derby.impl.sql.execute.UpdateResultSet.open(Unknown Source)
> 	at org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(Unknown Source)
> 	at org.apache.derby.impl.sql.GenericPreparedStatement.execute(Unknown Source)
> 	at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source)
> 	at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown Source)
> 	at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeUpdate(Unknown Source)
> 	at org.apache.derbyTesting.functionTests.tests.upgradeTests.BasicSetup.testTriggersWithLOBcolumns(BasicSetup.java:854)

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