Sighup is needed when processes (such as Postgres) write directly to log files. These files are open, and when you want to rotate the file, you have to tell the process to close the files so that it will start writing to a new file.
If you tell Postgres to log to rsyslog (or any other syslog daemon), the log data will be sent to rsyslog via UDP, TCP or a Unix socket. Postgres itself will not have any files open, so there is no need to sighup it.
You will have to sighup rsyslog in the host system, though.
Sighup is needed when processes (such as Postgres) write directly to log files. These files are open, and when you want to rotate the file, you have to tell the process to close the files so that it will start writing to a new file.
If you tell Postgres to log to rsyslog (or any other syslog daemon), the log data will be sent to rsyslog via UDP, TCP or a Unix socket. Postgres itself will not have any files open, so there is no need to sighup it.
You will have to sighup rsyslog in the host system, though.