How to send/receive parameters when using PostgreSQL NOTIFY with Java

Question

I'm using J2EE and my code is below

public class Notifier {

    private Connection conn;

    public void notifyThread() throws SQLException {
      conn  =   ConnectionManager.getConnection();
      Statement stmt = conn.createStatement();
      stmt.execute("NOTIFY notificationRecived");
      stmt.close();
    }
}

At the listener's end I'm using:

org.postgresql.PGNotification notifications[] = pgconn.getNotifications();

To extract the details of notification. Here I noticed that

notifications[i].getParameter();

Is a method to extract the data which is sent along with the NOTIFY statement. I saw few threads which suggest that we can pass data along with the NOTIFY statement like NOTIFY notificationRecived, "xyz" but this one throws an error at ,xyz.

Is there any other syntax to pass parameters along with NOTIFY?

Paul Roub · Accepted Answer · 2016-07-02 13:54:42Z

1

Here is the updated code

public void notifyThread() throws SQLException {
  conn    =   ConnectionManager.getConnection();
  Statement stmt = conn.createStatement();
  stmt.execute("SELECT pg_notify('notificationRecived', 'xyz');");
  stmt.close();    
}

To send a notification you can also use the function pg_notify(text, text). The function takes the channel name as the first argument and the payload as the second. The function is much easier to use than the NOTIFY command if you need to work with non-constant channel names and payloads.

edited Jul 2, 2016 at 13:54

Paul Roub

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answered Jun 30, 2016 at 6:38

NGoyal

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Comments

SerhiiOn · Accepted Answer · 2020-07-31 08:36:51Z

0

public void notifyThread() throws SQLException {
  conn  =   ConnectionManager.getConnection();
  Statement stmt = conn.createStatement();

  stmt.execute("NOTIFY notificationRecived, 'xyz'");

  stmt.close();
}

According to documentation: https://www.postgresql.org/docs/current/sql-notify.html

answered Jul 31, 2020 at 8:36

SerhiiOn

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