RE: proposal: Allocate work_mem From Pool

>> I think it would be better if work_mem was allocated from a pool
>> of  memory

> I think this has been proposed before, and the issue/objection
> with this idea is probably that query plans will be inconsistent,
> and end up being sub-optimal.

> work_mem is considered at planning time, but I think you only
> consider its application execution.  A query that was planned
>  with the configured work_mem but can't obtain the expected
> amount at execution time might perform poorly. Maybe it
> should be replanned with lower work_mem, but that would
> lose the arms-length relationship between the planner-executor.

> Should an expensive query wait a bit to try to get more
> work_mem? What do you do if 3 expensive queries are all
> waiting ?

Before I try to answer that, I need to know how the scheduler works.

Let's say there's a max of 8 worker process, and 12 queries trying to run.
When does query #9 run? After the first of 1-8 completes, simple FIFO?
Or something else?

Also, how long goes a query hold a worker process?  All the way to
completion?  Or does is perform some unit of work and rotate to
another query?

Joseph D Wagner

P.S.  If there's a link to all this somewhere, please let me know.
Parsing through years of email archives is not always user friendly or
helpful.