Tuesday, May 23, 2017

[google-cloud-sql-discuss] Re: postgresql random_page_cost

Please consider work_mem too, 4mb is awfully low too. I may be too used to custom tuning instances for my work load. I'd generally set work_mem closer to 30-35mb for a 12-16gb instance with 100 connections.

On Tuesday, May 23, 2017 at 7:49:44 PM UTC-5, Ankush Agarwal wrote:
Paul,

Thank you for your feedback and for bringing up the random_page_cost parameter. We have filed a bug internally to investigate the performance impact of random_page_cost.
Regarding shared_buffers, we currently have a default of 128MB for instances having < 60G RAM and 1/3*ram_size for instances with > 60G RAM. We have also started investigating setting an optimal shared_buffers for instances with < 60G RAM. Please let us know if you have any other questions or concerns.

On Tuesday, May 23, 2017 at 12:37:41 PM UTC-7, Paul Lamb wrote:
Didn't find anyone asking about this already here or on stack overflow. I'm assuming that the default value of 4 is being used for random_page_cost (I created a new pg instance today with 2 cpu/13gb memory, 100gb of ssd). This might have just been overlooked but that's an awfully high number. Most of the time for more modern san's a number in the 1.5-2.0 is considered conservative. Also, how are are shared_buffers getting set? For this instance I created today it's set to have 128mb for shared buffers.

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