Why do I receive a "java.lang​.OutOfMemo​ryError: Java heap space" error after upgrading to Database Toolbox 3.5.1 (R2009a)?

After upgrading to Database Toolbox 3.5.1 (R2009a) I receive the following error when executing a query:

 ??? Java exception occurred:

 java.lang.OutOfMemoryError: Java heap space

 at oracle.jdbc.driver.OracleStatement.prepareAccessors(OracleStatement.java:796)

 at oracle.jdbc.driver.OracleStatement.execute_maybe_describe(OracleStatement.java:949)

 at oracle.jdbc.driver.T4CStatement.execute_maybe_describe(T4CStatement.java:463)

 at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1037)

 at oracle.jdbc.driver.OracleStatement.executeQuery(OracleStatement.java:1183)

 at com.mathworks.toolbox.database.sqlExec.executeTheSelectStatement(sqlExec.java:170)

 Error in ==> cursor.cursor at 150

       resultSetVector = executeTheSelectStatement(curs.Cursor,curs.Statement);

 Error in ==> database.exec at 34

     curs=cursor(connect,sqlQuery);

In previous versions of the toolbox I never received this error.

Now I read that I can increase the Java heap space to prevent similar out of memory errors but I did not have to do this in the previous version. Also, the query which I execute does not operate on a large dataset.

Answer 1

[MathWorks Support Team]

In Database Toolbox 3.5.1 (R2009a) the default value of the JDBC property 'defaultRowPrefetch' was changed from 10 to 10000. This change should increase the performance of the toolbox, however it will also increase the memory requirements of the toolbox.

To prevent the out of memory error from occuring, you can change this property back to its default value; below instructions for this are given for different versions of the toolbox:

To change the property in Database Toolbox 3.5.1 (R2009a):

After creating the connection:

conn = database(....);

Run the following code:

h = conn.Handle;

h.setDefaultRowPrefetch(10);

To change the property in Database Toolbox 3.6 (R2009b):

Run the following code:

setdbprefs('DefaultRowPrefetch','10')

[Usha Duddu]

Hi Eric LePage

I understand you are running into "java.lang.OutOfMemoryError: Java heap space Exception in thread "AWT-EventQueue-0" error when executing a database query.

Are you getting the errors after following the suggested workaround on Database Toolbox of R2009a?

Please contact MathWorks Technical Support and raise a help ticket. I am sure our team will be very happy to help you.

Thank you

Usha