Re: Exception in thread "main" java.lang.OutOfMemoryError - Mailing list pgsql-novice

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@intelerad.com
www.intelerad.com

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