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From "Kathey Marsden (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3732) SQL Length function materializes lob into memory
Date Fri, 27 Jun 2008 18:29:45 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12608879#action_12608879
] 

Kathey Marsden commented on DERBY-3732:
---------------------------------------

I tried switching over to reflection and running with  IBM and Sun  JDK 1.4.2  and get an
OOM in client running with 16MB heap.  JDK 1.5 runs fine.  Embedded is also ok with JDK 1.4.2.
I'm investigating but if anyone knows of maybe some different behavior in client for JDK 1.4.2
that might cause this, let me know.


1) testBlobLength(org.apache.derbyTesting.functionTests.tests.memory.BlobMemTest)java.lang.OutOfMemoryError:
        at org.apache.derby.client.am.Cursor.get_VARCHAR_FOR_BIT_DATA(Cursor.java:647)
        at org.apache.derby.client.am.Cursor.getBytes(Cursor.java:1058)
        at org.apache.derby.client.am.CallableStatement.getBytesX(CallableStatement.java:676)
        at org.apache.derby.client.am.CallableLocatorProcedures.blobGetBytes(CallableLocatorProcedures.java:447)
        at org.apache.derby.client.am.BlobLocatorInputStream.readBytes(BlobLocatorInputStream.java:176)
        at org.apache.derby.client.am.BlobLocatorInputStream.read(BlobLocatorInputStream.java:135)
        at java.io.BufferedInputStream.read1(BufferedInputStream.java:237)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:294)
        at java.io.FilterInputStream.read(FilterInputStream.java(Compiled Code))
        at org.apache.derby.client.am.CloseFilterInputStream.read(CloseFilterInputStream.java:79)
        at java.io.FilterInputStream.read(FilterInputStream.java:110)
        at org.apache.derby.client.am.CloseFilterInputStream.read(CloseFilterInputStream.java:65)
        at org.apache.derbyTesting.functionTests.tests.memory.BlobMemTest.testBlobLength(BlobMemTest.java:124)
        at org.apache.derbyTesting.functionTests.tests.memory.BlobMemTest.testBlobLength(BlobMemTest.java:170)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:85)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:58)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java(Compiled
Code))
        at org.apache.derbyTesting.junit.BaseTestCase.runBare(BaseTestCase.java:104)
        at junit.extensions.TestDecorator.basicRun(TestDecorator.java:22)
        at junit.extensions.TestSetup$1.protect(TestSetup.java:19)
        at junit.extensions.TestSetup.run(TestSetup.java:23)
        at org.apache.derbyTesting.junit.BaseTestSetup.run(BaseTestSetup.java:57)
        at junit.extensions.TestDecorator.basicRun(TestDecorator.java:22)
        at junit.extensions.TestSetup$1.protect(TestSetup.java:19)
        at junit.extensions.TestSetup.run(TestSetup.java:23)
        at junit.extensions.TestDecorator.basicRun(TestDecorator.java:22)
        at junit.extensions.TestSetup$1.protect(TestSetup.java:19)
        at junit.extensions.TestSetup.run(TestSetup.java:23)
        at org.apache.derbyTesting.junit.BaseTestSetup.run(BaseTestSetup.java:57)
        at junit.extensions.TestDecorator.basicRun(TestDecorator.java:22)
        at junit.extensions.TestSetup$1.protect(TestSetup.java:19)
        at junit.extensions.TestSetup.run(TestSetup.java:23)

> SQL Length function materializes lob into memory
> ------------------------------------------------
>
>                 Key: DERBY-3732
>                 URL: https://issues.apache.org/jira/browse/DERBY-3732
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.3.3.0, 10.4.1.3, 10.5.0.0
>            Reporter: Kathey Marsden
>            Priority: Minor
>         Attachments: derby-3732_diff.txt, derby-3732_proto_diff.txt, derby-3732_skip2_diff.txt,
derby-3732_skip_diff.txt, LengthLargeLob.zip, LengthThruBlob.java
>
>
> Currently the SQL length function materializes the entire lob into memory. In SQLBinary.getLength()
we have 
> public final int	getLength() throws StandardException
> 	{
> 		if (stream != null) {
> 			if (streamValueLength != -1)
> 				return streamValueLength;
> 		}
> 		return (getBytes() == null) ? 0 : getBytes().length;
> 	}
> Which actually is doubly bad because we call getBytes twice and materialize it twice.
> It would be good to read the length from the stream if available and otherwise stream
the value to get the length, rather than materializing it into memory.
> To reproduce, run the attached repro.
> java -Xmx16M  LengthLargeLob
> It gives an out of memory exception
> Caused by: java.lang.OutOfMemoryError: Java heap space
>         at org.apache.derby.iapi.types.SQLBinary.readFromStream(SQLBinary.java:415)
>         at org.apache.derby.iapi.types.SQLBinary.readExternal(SQLBinary.java:318)
>         at org.apache.derby.iapi.types.SQLBinary.getValue(SQLBinary.java:220)
>         at org.apache.derby.iapi.types.SQLBinary.getBytes(SQLBinary.java:210)
>         at org.apache.derby.iapi.types.SQLBinary.getLength(SQLBinary.java:250)
>         at org.apache.derby.impl.sql.execute.BaseActivation.getDB2Length(BaseActivation.java:1684)
>         at org.apache.derby.exe.acf81e0010x011axa317x5db8x0000003d9dc81.e1(Unknown Source)
>         at org.apache.derby.impl.services.reflect.DirectCall.invoke(ReflectGeneratedClass.java:141)
>         at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.doProjection(ProjectRestrictResultSet.java:497)
>         at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.getNextRowCore(ProjectRestrictResultSet.java:291)
>         at org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl.getNextRow(BasicNoPutResultSetImpl.java:460)
>         at org.apache.derby.impl.jdbc.EmbedResultSet.movePosition(EmbedResultSet.java:423)
>         ... 2 more
> [
>  

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