Re: Memory usage with Postgres JDBC

I know that Barry Lind has plans to do so, but I'm not sure of his
schedule?

Dave
On Tue, 2002-07-23 at 04:49, Kovács Péter wrote:
> Anyone working on "internal cursor" support? (Or would not it be a better
> way to call it "implied cursor" support?)
>
> Pete
>
> -----Original Message-----
> From: Dave Cramer [mailto:Dave@micro-automation.net]
> Sent: Friday, July 19, 2002 4:51 PM
> To: Mike R
> Cc: pgsql-jdbc@postgresql.org
> Subject: Re: [JDBC] Memory usage with Postgres JDBC
>
>
> Mike,
>
> use cursors, unfortunately you will have to do this manually, as the
> driver doesn't support them internally ( yet ).
>
> Dave
> On Fri, 2002-07-19 at 10:21, Mike R wrote:
> > Hi,
> > We are running a Java application which can run against either a Postgres
> or
> > Oracle database using jdbc.
> > I noticed a dramatic difference in memory usage between the two databases,
>
> > presumably stemming from the different jdbc drivers.
> > The simple test program below connects to a database and does a select
> from
> > a table containing about 40000 records (select * from mytable).  When
> using
> > Oracle, the memory usage peaked at about 11Mb.  With the Postgres driver
> it
> > peaked at 75Mb.  I suspect that the PG jdbc driver brings back the entire
> > ResultSet all at once and keeps it in memory on the client, while the
> Oracle
> > driver probably fetches in blocks.
> >
> > Is there any way to reduce memory usage with Postgres?
> > I know there is a setFetchSize method in the Statement interface which
> > likely was intended for this very purpose.  Unfortunately, it isn't
> > implemented by the Postgres JDBC driver (...so much for standards).
> >
> > Any help on this matter would be greatly appreciated.
> > By the way, we cannot have different SQL code for the different databases.
>
> > It must be standard.  So using PostgreSQL specific commands is not an
> > option.
> >
> > Cheers,
> > Mike.
> >
> > (Other info: In both cases, the application is running on Windows2000.
> The
> > Postgres database is on a Linux machine while Oracle is on Windows2000.)
> >
> >
> > /** Postgres Code **/
> > import java.sql.*;
> > import java.io.*;
> >
> > public class JdbcCheckupPG
> > {
> >   public static void main (String args [])
> >        throws SQLException, IOException
> >   {
> >     DriverManager.registerDriver(new org.postgresql.Driver());
> >
> >     String user;
> >     String password;
> >     String database;
> >
> >     database="jdbc:postgresql://myserver:1234/mydatabase";
> >     user    ="postgres";
> >     password="";
> >
> >     System.out.flush ();
> >
> >     Connection conn = DriverManager.getConnection (database, user,
> > password);
> >     Statement stmt = conn.createStatement ();
> >     ResultSet rset = stmt.executeQuery ("select * from mytable");
> >
> >     while (rset.next ())
> >       System.out.println (rset.getString (1));
> >
> >     rset.close();
> >     stmt.close();
> >     conn.close();
> >   }
> > }
> >
> > /** Oracle Code **/
> > import java.sql.*;
> > import java.io.*;
> >
> > public class JdbcCheckupORA
> > {
> >   public static void main (String args [])
> >        throws SQLException, IOException
> >   {
> >     DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
> >
> >     String user;
> >     String password;
> >     String database;
> >
> >     database="jdbc:oracle:thin:@myserver:1521:mydatabase";
> >     user    ="test";
> >     password="test";
> >
> >     Connection conn = DriverManager.getConnection (database, user,
> > password);
> >     Statement stmt = conn.createStatement ();
> >     ResultSet rset = stmt.executeQuery ("select * from mytable");
> >
> >     while (rset.next ())
> >       System.out.println (rset.getString (1));
> >
> >     rset.close();
> >     stmt.close();
> >     conn.close();
> >   }
> > }
> >
> >
> >
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