about effective_cache_size
* What is the difference between shared_buffers and effective_cache_size?
* If I set effective cache size 1GB for db1 and 500 MB for db2, then what
will happen to the system memory usage?
Anyone please tell me.
In response to AI Rumman :
* What is the difference between shared_buffers and effective_cache_size?
effective_cache_size:
Sets the planner's assumption about the effective size of the disk cache
that is available to a single query. This parameter has no effect on the
size of shared memory allocated by PostgreSQL, nor does it reserve
kernel disk cache; it is used only for estimation purposes.
shared_buffers:
Sets the amount of memory the database server uses for shared memory
buffers.
It's all copied from the doc, there are much more details about this
parameters. Read the doc!
Regards, Andreas
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Andreas Kretschmer
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AI Rumman wrote:
* What is the difference between shared_buffers and effective_cache_size?
This whole topic is covered at
http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server and the
additional references that document leads to.
* If I set effective cache size 1GB for db1 and 500 MB for db2, then
what will happen to the system memory usage?
Nothing; effective_cache_size doesn't impact system memory usage
directly. And I don't think you can set effective_cache_size
differently for each database anyway.
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Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com www.2ndQuadrant.us