>> 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.
