Re: Single Instance of Backend

No, the postmaster is the "ringleader". When a client requests a
connection it spawns a new postgres process. That client will be
connected to that postgres process until the client disconnects (or
possibly "something bad" (tm) happens). If the max number of
connections has been reached  then Postmaster will return an error to
a client that attempts to connect.

The various processes communicate with each other to deal with
locks/MVCC and other issues. I have not dug into the guts of how they
communicate but it appears to be a combination of shared memory,
signals, and possibly sockets.

Cheers,
Steve

On Wednesday 18 June 2003 12:58 pm, Dennis Gearon wrote:
> I have heard several mentions of the requirements for single
> postmaster. Is a postmaster 'the backend'? Maybe I could define
> what I think is the current situation first:
>
>
> client1    client2     client3    ....
>
>   +-----------+-----------+---------+
>
>   V
> Postmaster
>
>   V
> OperSys
>
>   V
> Disks
>
> Is this correct?