Re: Don't see CLOSE packet been sent

Please post this on github as you will get more traction
https://github.com/pgjdbc/pgjdbc/issues

Does seem like a bug though.

Dave Cramer
www.postgres.rocks

On Sat, 6 Dec 2025 at 06:35, Manav Kumar <mkumar(at)yugabyte(dot)com> wrote:

> Hi Team,
> Writing to ask for a follow up. Can someone please clarify. I only see
> CLOSE been sent by driver when server returns an error message 'prepared
> statement does not exist".
>
> Thanks
> Manav
>
> On Thu, Dec 4, 2025 at 7:07 PM Manav Kumar <mkumar(at)yugabyte(dot)com> wrote:
>
>> Hi Team,
>> Wrote a simple below application to understand nature of CLOSE packet.
>> But i don't see the JDBC sending CLOSE packet. Any ideas what i can do
>> see CLOSE packet.
>> I'm compiling with:
>> javac -classpath /home/manavkumar/postgresql-42.7.1.jar sendClose.java &&
>> \
>> java -cp .:/home/manavkumar/postgresql-42.7.1.jar sendClose
>>
>> ```import java.sql.*;
>>
>> public class sendClose {
>>
>> public static void main(String[] args) {
>> Connection connection = null;
>> PreparedStatement pstmt1 = null, pstmt2 = null;
>>
>> try {
>> // prepareThreshold=1 is crucial here
>> connection = DriverManager.getConnection("jdbc:postgresql://
>> 10.150.3.175:5433/yugabyte?prepareThreshold=1", "yugabyte","yugabyte");
>>
>> // ---------------------------------------------------------
>> // CHANGE 1: Use placeholders (?)
>> // This forces the driver to use Extended Query Protocol (Parse/Bind)
>> // and create a named statement (e.g., "S_1") on the server.
>> // ---------------------------------------------------------
>> pstmt1 = connection.prepareStatement("insert into t_ values (?, ?)");
>> pstmt1.setInt(1, 1);
>> pstmt1.setInt(2, 2);
>> // Execute twice to ensure the driver switches to server-prepare mode
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> pstmt1.execute();
>> // ---------------------------------------------------------
>> // CHANGE 2: Close the statement
>> // The driver now marks "S_1" as closed internally and queues the packet.
>> // ---------------------------------------------------------
>> pstmt1.close();
>>
>> System.out.println("Statement 1 closed. Sending Statement 2 to flush the
>> buffer...");
>>
>> // ---------------------------------------------------------
>> // CHANGE 3: Send ANY other traffic
>> // The driver will attach the buffered "CLOSE S_1" packet
>> // to the front of this new request.
>> // ---------------------------------------------------------
>> pstmt2 = connection.prepareStatement("SELECT 1");
>> pstmt2.execute();
>> pstmt2.close();
>>
>> connection.close();
>> }
>> catch (Exception e) {
>> e.printStackTrace();
>> }
>> }
>> }
>>
>> ```
>>
>