On 4-Sep-06, at 8:07 AM, Guillaume Cottenceau wrote:
Dave Cramer <pg 'at' fastcrypt.com> writes:
Guillaume
1G is really not a significant amount of memory these days,
Yeah though we have 2G or 4G of RAM in our servers (and not only
postgres running on it).
That said 6-10% of available memory should be given to an 8.0 or
older version of postgresql
Newer versions work better around 25%
I'm not sure what you mean by mechanically removed from
effective_cache
I mean that when you allocate more memory to applications, the
consequence is less memory the OS will be able to use for disk
cache.
effective cache is really a representation of shared buffers plus OS
cache
Are you sure the shared buffers should be counted in? As I
understand the documentation, they should not (as shared buffers
is allocated memory for the OS, not part of "kernel's disk
cache"):
Yes, I am sure this should be counted, however effective_cache is not
actually allocating anything so it doesn't have to be exact, but it
has to be in the correct order of magnitude
Sets the planner's assumption about the effective size of the
disk cache (that is, the portion of the kernel's disk cache
that will be used for PostgreSQL data files). This is
measured in disk pages, which are normally 8192 bytes each.
The default is 1000.
--
Guillaume Cottenceau
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