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

I don't think that your JDBC driver does not honor the fetch-size.
See: http://jdbc.postgresql.org/todo.html

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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