Re: Help - lo_close: invalid large obj descriptor - Mailing list pgsql-jdbc

Toby,

You need to have autocommit turned off in order to use large objects.
If I add a call to setAutocommit(false) for the connection everything
works fine.

thanks,
--Barry


Toby wrote:
> I've read the docs, I've searched the web.
>
> I'm running PGSql 7.3.4 under Cygwin 1.3.22.1, J2SE 1.4.2, latest stable
> JDBC v3 drivers (pg73jdbc3.jar). This is all running on the same
> machine, a dual AMD with 1GB memory.
>
> Accessing the database works fine, but when I try to write to a newly
> created LargeObject it always fails with
>
> org.postgresql.util.PSQLException - FastPath call returned ERROR:
> lo_write: invalid large obj descriptor (0)
>
> The code below illustrates this.
>
> The code is actually going to be used within a Tomcat webapp, but I had
> to use Jdbc3ConnectionPool since that was the only pool that returned
> connections that were castable to a PGConnection. I get the same error
> from inside and outside Tomcat. Thought the error might be related to
> permissions writing large objects so I tried the following which didn't
> help.
>
>         GRANT ALL ON "pg_largeobject" TO "web";
>
> I also tried not using the connection pool, and instead just using the
> straight DriverManager.getConnection() instead, but that fails on the
> lo.write() call too.
>
> I've had large objects working fine on another project (same dev
> machine) a coupla years ago (pg 7.2.x), so I don't think its a case of
> HOW I'm doing it, I suspect there's a bug.
>
> Can someone shed some light?
>
>
> import java.io.File;
> import java.io.FileInputStream;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.SQLException;
>
> import org.postgresql.PGConnection;
> import org.postgresql.jdbc3.Jdbc3ConnectionPool;
> import org.postgresql.largeobject.LargeObject;
> import org.postgresql.largeobject.LargeObjectManager;
>
> public class TestHarness
> {
>     public static void main(String[] args)
>     {
>         LargeObject lo = null;
>         Connection conn = null;
>         try
>         {
>             //get a connection that's PGConnection-castable.
>             //PoolingDataSource- tried 'n died
>             //Jdbc3PoolingDataSource- tried 'n died
>             Jdbc3ConnectionPool source = new Jdbc3ConnectionPool();
>             source.setServerName("ash");
>             source.setDatabaseName("adserver");
>             source.setUser("web");
>             source.setPassword("web");
>             source.setDefaultAutoCommit(false);
>
>             //just to be sure - it always says true so that's good
>             //Class.forName("org.postgresql.Driver");
>             //conn =
> DriverManager.getConnection("jdbc:postgresql://ash/adserver", "web",
> "web");
>             conn = source.getConnection();
>             System.out.println(conn.getAutoCommit());
>
>             //this only works for connections from Jdbc3ConnectionPool
>             PGConnection pgconn = (PGConnection)conn;
>
>             //create the largeobject and prepare to write to it
>             LargeObjectManager lom = pgconn.getLargeObjectAPI();
>             int oid = lom.create(LargeObjectManager.READ |
> LargeObjectManager.WRITE);
>             lo = lom.open(oid, LargeObjectManager.WRITE);
>
>             //the thing to write
>             File file = new File("D:\\downloads\\images\\banner.GIF");
>             FileInputStream fis = new FileInputStream(file);
>
>             //prepare a buffer (small enough to force multiple loop
> iterations
>             //so we test it properly)
>             byte buff[] = new byte[1024];
>
>             //now write the image
>             int bytes_read;
>             while ((bytes_read = fis.read(buff, 0, buff.length)) > 0)
>             {
>                 System.out.println("bytes_read=" + bytes_read);
>                 //ERROR HAPPENS NEXT
>                 //ERROR HAPPENS NEXT
>                 //ERROR HAPPENS NEXT
>                lo.write(buff, 0, bytes_read);
>             }
>
>             //clean up
>             fis.close();
>             System.out.println("done");
>         }
>         catch (Exception e)
>         {
>             System.out.println(e.getClass().getName() + " - " +
> e.getMessage());
>         }
>         finally
>         {
>             if (lo != null)    try{lo.close();}catch (SQLException e){}
>             if (conn != null) try{conn.close();}catch (SQLException e){}
>         }
>     }
> }
>
>