Re: work_mem

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Hi All

One basic doubt. 

Whether work_mem is allocated for each clients connected to Database or for against the Sort Operations(Queries) in database? Please clarify

Case 1: 
work_mem=4m
Total Sessions connected=100
Total=400M 

Or Case 2
work_mem=4m
Total Sort operations at DB now=50
Total work_mem=200M

Please clarify at high level whether Case 1 is true or Case 2 is true?


Regards

Sasi
On Friday, 2 April, 2021, 09:04:56 pm IST, Bruce Momjian <bruce@xxxxxxxxxx> wrote:


On Fri, Apr  2, 2021 at 03:25:04PM +0000, Campbell, Lance wrote:
> Thanks for sharing this thread.  My suggestion of having a work_mem_stack_size
> is the same concept mentioned in this thread regarding having a work_mem_pool.
> I prefer this later term rather than the one I was using.  When the work mem
> pool is exhausted PostgreSQL just uses temp files for work_mem.  With current
> statics for temp files and with a new stats on a work mem pool usage a user
> could fine tune memory much more precisely.  It would leave the “art of memory
> tuning” behind.  The other added benefit is that people would have a better
> understanding of how work_mem is used by naturally having to explain what a
> work_mem_pool is and when it is drawn on.  There are probably a lot of
> PostgreSQL instance that would run faster just by having the confidence to
> increase the size of work_mem.  I am sure many instances have this value set to
> low.

Uh, did you read the blog before it, referenced in that blog entry:

    https://momjian.us/main/blogs/pgblog/2018.html#December_7_2018

Even if we have a pool, it is still complex to configure memory, but it
might help.


--
  Bruce Momjian  <bruce@xxxxxxxxxx>        https://momjian.us
  EDB                                      https://enterprisedb.com

  If only the physical world exists, free will is an illusion.




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