Re: tuplestore potential performance problem

Has this been addressed?

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Hitoshi Harada wrote:
> 2008/12/3 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> > If this means a lot of contortion/complication in the upper-level code,
> > seems like it'd be better to address the performance issue within
> > tuplestore/buffile. We could keep separate buffers for write and read
> > perhaps. But do you have real evidence of a performance problem?
> > I'd sort of expect the kernel's disk cache to mitigate this pretty well.
> >
> > regards, tom lane
> >
> I don't have real evidence but reasoned it. No strace was done. So it
> may not be cased by flushing out but this commit gets performance
> quite better, to earlier patch performance, around 44sec from around
> 76sec.
>
> http://git.postgresql.org/?p=~davidfetter/window_functions/.git;a=commitdiff;h=87d9b8ac5dca9fae5f3ac4f3218d8fb4eca8b5b0;hp=f1976a9d002b20006ac31ca85db27abcf56e9ea2
>
> where pos = -1 means spool all rows until the end.
>
> The "earlier" approach was buffering all the table and the newer
> Heikki's approach was buffer on row by row while reading. The newest
> is buffering row by row while reading during in memory, and holding
> all the remaining tuples before reading after out to file, something
> like hybrid method.
>
> Regards,
>
> --
> Hitoshi Harada
>
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