variable proxy_read_timeout ?

[Brice Figureau]

Hi,

Running nging 0.5.16 it seems impossible to write something like this:

server {
...
 set $read_timeout 90;

  if ( $query_string ~* special-paramater ) {
	set $read_timeout 1200;
  }

  location ~* .+\.php$ {
	proxy_pass http://127.0.0.1;
	proxy_read_timeout $read_timeout;
  }
...
}

Nginx complains with: 
2007/05/28 12:05:33 [emerg] 22267#0: the "proxy_read_timeout" directive
invalid value in /etc/nginx/nginx.conf:155

My problem is that the upstream server can take a quite long time to
answer some queries (long computations).
I don't have the possibility to modify the upstream server to send a few
bytes every read_timeout seconds, and I don't want to have all the
requests to the upstream server with a proxy_read_timeout of 1200s
(because it won't detect unresponsive upstream server then).

Any idea on how I can work-around that ?
Thanks,
-- 
Brice Figureau <brice+nginx at daysofwonder.com>