work_mem and maintenance_work_mem limits for managed postgres on Gen5 instance

Question

There is a limit on work_mem and maintenance_work_mem parameters for server configurations, which is setting the max values to 2097171, although there is much larger amount memory available on the machine.

Why is there a limit on these configs?

Answer 1

Hi @Deniz Durmus Thank you for posting your question on Microsoft Q&A.

work_mem is assigned per connection so the total RAM used is work_mem * concurrent connectons – thus an upper limit is needed to avoid starving processes.
Also maintenance_work_mem being a background process is designed to have a upper limit so that by mistake we do not over assign the memory and starve other processes.

https://www.postgresql.org/docs/12/runtime-config-resource.html

Hope that answer your question

Regards,
Oury