So it turned out, that there was something wrong with the connection. It was created with that code:
void PostgresqlDatabase::pgMDBconstruct(std::string host, std::string port,
std::string user, std::string password, std::string dbname )
{
std::string conn_info = "host=" + host + " port=" + port +
" user=" + user + " password=" + password + " dbname=" + dbname;
connection_= PQconnectdb(conn_info.c_str());
if (PQstatus(connection_)!=CONNECTION_OK)
{
ROS_ERROR("Database connection failed with error message: %s", PQerrorMessage(connection_));
}
}
With host=192.168.10.100, port=5432, user=turtlebot, password= , dbname=rosdb.
But an empty username doesn't satisfy the usage of PQconnectdb, which, for some parsing-reason, caused it to login to the database "turtlebot". That database unfortunately existed on my server. And there it - of course - didn't get any notifications sent out in the "rosdb"-database and had a good connection.
What an, for me, awkward and unlucky behaviour.