Michael Paesold wrote: > Stefan Kaltenbrunner wrote: > >> hubert depesz lubaczewski wrote: >> >>> On 3/4/06, Stefan Kaltenbrunner <[EMAIL PROTECTED]> wrote: >>> >>>> forgot to mention that this is 8.1.3 compiled from source. Further >>>> testing shows that not only CREATE INDEX has some issue with large >>>> maintenance_work_mem settings : >>> >>> >>> what does it show: >>> cat /proc/sys/kernel/shmmax >> >> >> 1421326592 >> >> not that I think it is related to the problem at all. > > > I can second that. Maintenance work mem is not allocated in shared memory. > >> It looks like I'm >> hitting the MaxAllocSize Limit in src/include/utils/memutils.h. > > > There are two issues you have mentioned. This one is more obvious: the > limitation of the memory that can be allocated.
yes > > The other one is the very bad performance for index creation. I can only > guess, but is sound like this is related to the recent discussion on > hackers about issues with the qsort performance. If the theory is true, > your index creation should be much faster with a much lower setting for > maintenance_work_mem, so that it uses external sort. > > See the discussion starting here: > http://archives.postgresql.org/pgsql-hackers/2006-02/msg00590.php I was following this thread - and it was partly a reason why I'm playing with that(the CREATE INDEX on that table finished after about 12 hours with a bit less 2GB for maintenance_work_mem(for comparision it took me only about 2,5hours to create this table) . I'm currently testing who long it takes with very low settings to force an external sort. Stefan ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
