> changing it; I've applied a patch for that. I'm still not quite
> convinced that Ivan isn't seeing some other issue though.
Thank you
> In the meantime, I noticed something odd while experimenting with your
> test case: when running with default maintenance_work_mem = 16MB,
> there is a slowdown of 3x or 4x for the un-ordered case, just as you
> say. But at maintenance_work_mem = 200MB I see very little difference.
> This doesn't make sense to me --- it seems like a larger workspace
> should result in more difference because of greater chance to dump a
> lot of tuples into the index at once. Do you know why that's happening?
I suppose, if maintenance_work_mem is rather big then all data of index
accumulates in memory and so it writes at disk at once. With that test's options
size of index is equal to 40Mb.
--
Teodor Sigaev E-mail: teodor@sigaev.ru
WWW: http://www.sigaev.ru/