Re: [HACKERS] Slow count(*) again...

Mark Kirkwood <mark.kirkwood@xxxxxxxxxxxxxxx> · Fri, 04 Feb 2011 14:28:08 +1300



    On 04/02/11 13:49, Jeremy Harris wrote:
    On
      2011-02-03 21:51, Mark Kirkwood wrote:
      

      The cases I've seen in production
        typically involve "outgrowing" optimizer parameter settings:
        (e.g work_mem, effective_cache_size) as the application dataset
        gets bigger over time.
        

      An argument in favour of the DBMS maintaining a running estimate
      of such things.
      

        That is an interesting idea - I'm not quite sure how it could
        apply to server config settings (e.g work_mem) for which it
        would be dangerous to allow the server to increase on the fly,
        but it sure would be handy to have some sort of query execution
        "memory" so that alerts like:

        
        "STATEMENT: SELECT blah  : PARAMETERS blah: using temp file(s),
        last execution used memory"

        
        could be generated (this could be quite complex I guess,
        requiring some sort of long lived statement plan cache).

        
        Cheers

        
        Mark