Re: Exception in thread "main" java.lang.OutOfMemoryError

Richard,
I'm not sure about all operating systems, but on Windows 2000 and XP
you can add a flag -Xmx___M to your java command line to set the maximum
program heap size. The default Java heap maximum is 64 MB. If your test
machine has a reasonably good amount of RAM, you could insert -Xmx300M or
-Xmx500M to your command line and see if you get the same error.
And you may be misunderstanding what setFetchSize(int) does. It does
not control the maximum amount of data retrieved, just how many rows are
retrieved at a given time. Maybe you want to use setMaxRows(int) instead,
at least for testing. For more information, you can look at
http://www.jguru.com/faq/view.jsp?EID=462124
I hope this helps.

-Mike

On 3/13/06, Richard Kut <rkut(at)intelerad(dot)com> wrote:
>
> Hello!
>
> I am trying to use a cursor in Java to fetch multiple rows at
> once. The code
> seems to connect to the database okay, and seems to be fetching records,
> but
> then it fails with the error:
>
> Exception in thread "main" java.lang.OutOfMemoryError
>
>
> Here is the Java code:
>
>
> import java.sql.*;
>
> /*
> * To compile:
> *
> * /usr/bin/jikes -source 1.4
> -bootclasspath
> /usr/java/j2sdk1.4.2_02/jre/lib/rt.jar:/usr/java/j2sdk1.4.2_02/jre/lib/jsse.jar:/usr/java/j2sdk1.4.2_02/jre/li
>
> b/jce.jar test_connect.java
> *
> *
> * To run:
> *
> * java
> -cp /usr/share/java/postgresql-
> 8.1-404.jdbc2.jar:/usr/java/j2sdk1.4.2_02/jre/lib/rt.jar:/usr/java/j2sdk1.4.2_02/jre/lib/jsse.jar:/usr/java/j2sdk1.4.
> 2_02/jre/lib/jce.jar:. test_connect
> */
> class test_connect
> {
> private static Connection connectToDb( String dbName,
> String username,
> String password ) throws
> Exception
> {
> System.out.println( "Connecting to DB " + dbName + ", username " +
> username );
> String dbDriver = "org.postgresql.Driver";
> String url = "jdbc:postgresql://imsstd4/" + dbName;
> Class.forName( dbDriver ).newInstance();
>
> System.out.println( "Connecting to " + url + " with user " +
> username
> + " and pass " + password );
>
> Connection connection = DriverManager.getConnection( url,
> username,
> password );
>
> System.out.println( "Connection successful" );
>
> return connection;
> }
>
> private static void executeQuery( Connection connection ) throws
> SQLException
> {
> String sql = "SELECT * FROM pid, pv1 where
> pid.patient_id_internal_id
> = pv1.patient_id_internal_id";
>
> System.out.println( "Executing query: " + sql );
> Statement st = connection.createStatement();
>
> System.out.println( "Setting cursor size to 50 rows." );
> st.setFetchSize( 50 ); // turn on cursor
> ResultSet rs = st.executeQuery ( sql );
> System.out.println( "Got 50 results. Now walking them..." );
> int i = 0;
> while ( rs.next() )
> {
> // Do not print anything here for now
> i++;
> System.out.println( "Row " + i );
> }
> System.out.println( "Result set consumed " + i + " rows." );
> }
>
> public static void main( String[] args )
> {
> System.out.println( "Starting up..." );
>
> try
> {
> Connection connection = connectToDb( "hl7segmentsihe", "hl7",
> "segments" );
>
> executeQuery( connection );
> }
> catch ( Exception e )
> {
> System.out.println( "Got exception " + e );
> e.printStackTrace();
> }
> }
> }
>
>
> Here is the program output:
>
>
> Starting up...
> Connecting to DB hl7segmentsihe, username hl7
> Connecting to jdbc:postgresql://imsstd4/hl7segmentsihe with user hl7 and
> pass
> segments
> Connection successful
> Executing query: SELECT * FROM pid, pv1 where pid.patient_id_internal_id =
> pv1.patient_id_internal_id
> Setting cursor size to 50 rows.
> Exception in thread "main" java.lang.OutOfMemoryError
>
>
> What did I do wrong? Any help would be appreciated.
>
>
> --
> Regards,
>
> Richard Kut
> Database Administrator
> Research & Development
> Intelerad Medical Systems Inc.
> 460 Ste-Catherine West, Suite 210
> Montreal, Quebec, Canada H3B 1A7
> Tel: 514.931.6222 x7733
> Fax: 514.931.4653
> rkut(at)intelerad(dot)com
> www.intelerad.com
>
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