Hi,
> Can I add SHM with merely by managing the entry in sysctl.conf? My
> current values:
>
> kernel.shmmax = 536870912
> kernel.shmall = 536870912
>
> My "shared_buffers" in postgresql.conf is "20000". From the website
> http://www.desknow.com/kb/idx/12/061/article/ I notice that shmmax
> should be sharedbuffer*8192, so I suppose my shmmax can be much lower
> than the above, but I raised it for performance. Am I wrong to do so?
You need to configure the kernel so it allows processes to use more shared
memory. This does not mean that a process automatically uses it. For
PostgreSQL you will need to increase shared_buffers to make it use the extra
available shared memory. With your shared memory settings you can probably
increase shared_buffers to about 65000.
With the 'ipcs' command you can see how much shared memory PostgreSQL uses.
Look under 'Shared Memory Segments' to memory owned by user postgres.
- Sander