>> the only problem is because if we need to tune Postermaster to use
>> large buffer while system havn't so many SYSV shared memory, in many
>> systemes, we need to recompile OS kernel, this is a small problem to install
>> PGSQL to product environment.
Of course, if you haven't got mmap(), a recompile won't help ...
I'd be somewhat more enthusiastic about mmap if I thought we could
abandon the SysV shmem support completely, but I don't foresee that
happening for a long while yet.
regards, tom lane