Обсуждение: 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 -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header) GnuPG: 0x31720C99, 1006 CCB4 A326 1D42 6431 2EB0 389D 1DC2 3172 0C99
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. -- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.us