Highload website database architecture

[a]

Hi,

I am building a web app backed by database postgresql and currently the
site is under a humongous torrent of hits. I have a question regarding
the database backend config.

The database folder has a file called postgresql.cons where we can
specify no of active connections to the database -N which is currently
1024 and also specify the shared buffers. Is there any thumbrule in
deciding the -N and also the no of shared buffers for my config of 4
frontend servers and 1 database backend server. There is no global or
memcached mechanisms in use.

Any pointers would be greatly appreciated.

Thanx
a