max_connections and shared_buffers

Hi,

1) I saw a comment from experts-exchage regarding shared_buffers,
where max_connections were 600

"2000 shared buffers were for 40 connections
For 600 connections it looks more like 30000 shared buffers - to prevent
weekly slowdown.
i.e 8KB*30000 = 240MB

16M work_mem * 600 = 9600MB maximum when everyone is connected. "

Can anybody explain the logic behind the calculation?

Why 30000 shared buffers is suggested for 600 connections.

Postgresql help says "This setting must be at least 128 kilobytes and at
least 16 kilobytes times max_connections
<mk:@MSITStore:C:\Program%20Files\PostgreSQL\8.2\pgAdmin%20III\docs\en_U
S\pgadmin3.chm::/pg/runtime-config-connection.html#guc-max-connections>
."

2) I want to set max_connections=1024

Can anybody help to suggest a proper value for shared buffers for the
settings ( if no other settings are counted )

Anoo

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