Reading pg walsender.c, it seems repl keep alive is based on receivin…

…g replication messages,

so send standby status instead of plain ping

flow/connectors/postgres/postgres.go

@@ -139,7 +139,13 @@ func (c *PostgresConnector) ReplKeepAlive() (time.Duration, error) {
 func (c *PostgresConnector) ReplPing() error {
 	if c.replLock.TryLock() {
 		defer c.replLock.Unlock()
-		return c.replConn.Ping(c.ctx)
+		if c.replState != nil {
+			return pglogrepl.SendStandbyStatusUpdate(
+				c.ctx,
+				c.replConn.PgConn(),
+				pglogrepl.StandbyStatusUpdate{WALWritePosition: c.replState.Offset},
+			)
+		}
 	}
 	return nil
 }