Hello John,
>> we see up to 10x performance increase with bigger shared_buffers in case >> of this database. Main database entities are about 20GB in size and we see >> that performance drops considerably when running with smaller >> shared_buffers smaller then that. >> >> > do you adjust effective_cache_size accordingly? with the smaller > shared_buffers, we typically find at least half or more of physical memory > is available as OS level disk cache, as shown by the 'cached' output of > 'free' or whatever after the system has been running long enough to fully > populate its disk cache. this parameter has a significant performance > impact on the planner's estimation of the best way of executing given > queries. also, especially if you're executing queries that process a lot > of rows and have to do sorts and such, increasing work_mem is quite helpful. > > Yes, the effective_cache_size is set to the the 50% of the RAM = 64GB, but as I mentioned already, we are measuring considerable performance increase when increasing shared_buffers to the values, when it fits most important tables completely. Regards, -- Valentine