Re: Re[2]: [HACKERS] \dt and disk access

>
> I don't believe the data is almost-sorted.

I am going to recant this.  Often, the data is already sorted, but often
it is not.

>
> >
> >
> > How about using a heap sort?  Works in order of magnitude better on
> > almost-sorted data than the quick sort.
> >
> > I have the code if anyone is interested. (C++, though.)
> >
> > Leo
> > _______________________________________________________________________________
> > Subject: Re: [HACKERS] \dt and disk access
> > From:    <maillist%candle.pha.pa.us@interlockp.lubrizol.com> at LZ-INTERNET
> > Date:    6/23/97  10:16 PM
> >
> > > >From what I remember, the quick sort algorithm works just as fast on
> > > sorted data as on unsorted data.  In other words, the algorithm does not
> > > take advantage of the fact that the data is sorted.
> > >
> > > On the other hand, if you go to something like bubble sort, it will
> > > work faster than quick sort if the data is sorted and you are adding one
> > > more item, but on unsorted data it takes an enormously longer length of
> > > time to sort a large list.
> > >
> >
> > One thing I am going to look into is replacing the btree-build in the
> > current psort with a qsort of HeapTuple pointers.
> >
> > --
> > Bruce Momjian
> > maillist@candle.pha.pa.us
> >
> >
> >
> >
> >
>
>
> --
> Bruce Momjian
> maillist@candle.pha.pa.us
>
>


- --
Bruce Momjian
maillist@candle.pha.pa.us

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