Обсуждение: Diffrence between 8.0.3 and 8.1.3

Hi,

I use this JDBC Driver :
JDBC driver build number : 8.1.407-JDBC3
Server version : test do on 8.0.3 (linux), 8.1.3 (linux) and 8.1.2 (windows)

I have problem with the method getColumnDisplaySize in ResultSetMetaData class.

I have this java program:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement ;
import java.util.Properties;

public class Test {
  public static void main(String[] args) {
    try {
      Properties props = new Properties();
      Statement stmt = null;

      Class.forName ("org.postgresql.Driver");
      props.put("user","xxxxx");
      props.put("password","xxxxx");
      Connection conn = DriverManager.getConnection("jdbc:postgresql://myhost/mydatabase", props);


      try {
        String SQLselect = "SELECT col1, cast(' ' as varchar(3)) as mycol FROM mytable";
        stmt = conn.createStatement();
        ResultSet res = stmt.executeQuery(SQLselect);
        ResultSetMetaData resMD = res.getMetaData();
        System.out.println(resMD.getColumnDisplaySize(2));
        res.close();
        stmt.close();
      } catch ( Exception e ) {
        System.out.println ("Error 1 : " + e.getMessage());
        e.printStackTrace();
      }
      finally {
        conn.close();
      }
    } catch ( Exception e) {
      System.out.println("Error 2 : " + e.getMessage());
      e.printStackTrace();
    }
  }
}

When i connect to 8.0.3 database the methode getColumnDisplaySize return 3, a good value
When i connect to 8.1.2 or 8.1.3 database the methode getColumnDisplaySize return -5, a bad value.

I saw the source of the JDBC Driver and i saw the difference is in data read on socket in the method receiveFields in QueryExecutorImpl class.
When i connect to 8.0.3 database, on this line of the method :
  ...
  int typeModifier = pgStream.ReceiveIntegerR(4);
  ...
typeModifier is set to 7.

When i conenct to 8.1.2 or 8.1.3, typeModifier is set to -1

Is it normal ?  Someone can explain this ?

Regards,

--
Yann

On Mon, 3 Jul 2006, Yann PICHOT wrote:

> I use this JDBC Driver :
> JDBC driver build number : 8.1.407-JDBC3
> Server version : test do on 8.0.3 (linux), 8.1.3 (linux) and 8.1.2 (windows)
>
> I have problem with the method getColumnDisplaySize in ResultSetMetaData
> class.
>
>       String SQLselect = "SELECT col1, cast(' ' as varchar(3)) as mycol
> FROM mytable";
>       stmt = conn.createStatement();
>       ResultSet res = stmt.executeQuery(SQLselect);
>       ResultSetMetaData resMD = res.getMetaData();
>       System.out.println(resMD.getColumnDisplaySize(2));
>
> When i connect to 8.0.3 database the methode getColumnDisplaySize return 3,
> a good value
> When i connect to 8.1.2 or 8.1.3 database the methode getColumnDisplaySize
> return -5, a bad value.
>

I cannot reproduce this with a 8.1.4 database and nothing in the
8.1.3 -> 8.1.4 release notes suggest that this behavior should have
changed.  Are you sure you're exactly describing your test, jdbc driver,
and server versions?

Kris Jurka

---------- Forwarded message ----------
From: Yann PICHOT <ypichot@gmail.com>
Date: 4 juil. 2006 10:07
Subject: Re: [JDBC] Diffrence between 8.0.3 and 8.1.3
To: Kris Jurka <books@ejurka.com>



--
Yann

On Wed, 5 Jul 2006, Yann PICHOT wrote:

> When i use this SQL request : SELECT col1, cast(' ' as varchar(3)) as mycol
> FROM mytable, getColumnDisplaySize return -5.
> When i use this SQL request : SELECT col1, cast(' ' as varchar(3)) as mycol,
> getColumnDisplaySize return 3 !!!!
>

OK, I misunderstood your test case and was only looking at the second
version which works.  As you noted earlier the server is responding with a
different typmod value, so this is not a JDBC problem, but a server
regression and I've forwarded this on to the -bugs list.  To summarize for
them:

In 8.0 "SELECT ' '::varchar(3) FROM tab" retained the typmod value
specified in the query, but in 8.1 it is lost and -1 is used instead.

Kris Jurka

Thanks, i'll follow the problem in the bug list.

--
Yann