On 25/05/10 19:49, MMK wrote:
Hello All:
In the code (costsize.c), I see that effective_cache_size is set to
DEFAULT_EFFECTIVE_CACHE_SIZE.
This is defined as follows in cost.h
#define DEFAULT_EFFECTIVE_CACHE_SIZE 16384
But when I say
show shared_buffers in psql I get,
shared_buffers ---------------- 28MB
In postgresql.conf file, the following lines appear
shared_buffers = 28MB # min 128kB # (change
requires restart)#temp_buffers = 8MB # min 800kB
So I am assuming that the buffer pool size is 28MB = 28 * 128 = 3584 8K pages.
So should effective_cache_size be set to 3584 rather than the 16384?
No. Please see the manual for what effective_cache_size means:
http://www.postgresql.org/docs/8.4/interactive/runtime-config-query.html#GUC-EFFECTIVE-CACHE-SIZE
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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