Shared Memory/Shared Buffers

[Alex Turner]

I have noticed that I can't set the shared buffers above 15512 which
is exactly 128MB of RAM. Even if I set /proc/sys/kernel/shmmax above
that, postgres refuses to start with a setting over 128MB.

Anyone have any ideas about this?

I guess there are a couple of questions - would I ever need a shared
buffers setting over 128MB? And if I do, how can I set it? The
database performs a lot of searches that are very heavy on seq scans
on a couple of tables, one with 35k rows that joins agains one with 2m
rows. The results are always sorted.

The system is Running SuSe 9.2 with kernel 2.6.8 on 2xAMD Opteron with 4GB RAM

Alex Turner
NetEconomist

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[Tom Lane]

Alex Turner <armtuk@gmail.com> writes:

> I have noticed that I can't set the shared buffers above 15512 which
> is exactly 128MB of RAM. Even if I set /proc/sys/kernel/shmmax above
> that, postgres refuses to start with a setting over 128MB.

Check your shmall setting, too.

regards, tom lane

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